diff --git a/language.version b/language.version
index 26ffb716e..34c3f2847 100644
--- a/language.version
+++ b/language.version
@@ -1,3 +1,3 @@
 [default]
-SWWM_MODVER="\cyDEMOLITIONIST \cw1.3pre r1055 \cu(Mon 18 Dec 23:21:59 CET 2023)\c-";
-SWWM_SHORTVER="\cw1.3pre r1055 \cu(2023-12-18 23:21:59)\c-";
+SWWM_MODVER="\cyDEMOLITIONIST \cw1.3pre r1056 \cu(Tue 19 Dec 11:46:29 CET 2023)\c-";
+SWWM_SHORTVER="\cw1.3pre r1056 \cu(2023-12-19 11:46:29)\c-";
diff --git a/zscript/dlc1/swwm_mister_fx.zsc b/zscript/dlc1/swwm_mister_fx.zsc
index 1b9cbe1d2..072e00176 100644
--- a/zscript/dlc1/swwm_mister_fx.zsc
+++ b/zscript/dlc1/swwm_mister_fx.zsc
@@ -1039,19 +1039,16 @@ Class MisterGrenade : Actor
 		if ( bNoProx ) return;
 		// "safe delay" for main grenade
 		if ( !bAMBUSH && (ReactionTime > default.ReactionTime-20) ) return;
-		bool breakout = false;
-		foreach ( s:level.Sectors )
+		let bt = BlockThingsIterator.Create(self,bAMBUSH?80:120);
+		while ( bt.Next() )
 		{
-			for ( Actor t=s.thinglist; t; t=t.snext )
-			{
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),bAMBUSH?80:120) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
-				special1++;
-				tracer = t;
-				breakout = true;
-				break;
-			}
-			if ( breakout ) break;
+			let t = bt.Thing;
+			if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),bAMBUSH?80:120) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+			special1++;
+			tracer = t;
+			break;
 		}
+		bt.Destroy();
 	}
 
 	// quicksort (seeking candidates)
diff --git a/zscript/handler/swwm_handler_debugrender.zsc b/zscript/handler/swwm_handler_debugrender.zsc
index e6f9de77b..a56b52050 100644
--- a/zscript/handler/swwm_handler_debugrender.zsc
+++ b/zscript/handler/swwm_handler_debugrender.zsc
@@ -102,15 +102,21 @@ extend Class SWWMHandler
 		if ( !swwm_debugview ) return;
 		// prepare projection data, we're going to need this
 		SWWMUtility.PrepareProjData(projdata,e.ViewPos,e.ViewAngle,e.ViewPitch,e.ViewRoll,players[consoleplayer].fov);
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		foreach ( s:level.Sectors )
 		{
-			if ( (a == players[consoleplayer].Camera) && !(players[consoleplayer].cheats&CF_CHASECAM) ) continue;
-			if ( a.bINVISIBLE && !(a is 'DynamicLight') ) continue;
-			if ( (a is 'Inventory') && Inventory(a).Owner ) continue;
-			if ( (a is 'SWWMPickupFlash') && (a.CurState == a.FindState('Pickup')) ) continue;
-			if ( (a is 'SWWMShadow') || (a is 'SWWMItemOverlay') || (a is 'HeadpatTracker') || (a is 'SWWMTeleportLine') || (a is 'SWWMTeleportDest') ) continue;
-			if ( a.Distance3DSquared(e.Camera) > 1000000 ) continue;
-			DrawActor(e,a);
+			// don't check sectors that aren't within bounds, saves some time
+			if ( !BoxInSectorBounds(s,players[consoleplayer].Camera.pos.xy,1000,players[consoleplayer].Camera.CurSector.PortalGroup) )
+				continue;
+			for ( Actor a=s.thinglist; a; a=a.snext )
+			{
+				if ( (a == players[consoleplayer].Camera) && !(players[consoleplayer].cheats&CF_CHASECAM) ) continue;
+				if ( a.bINVISIBLE && !(a is 'DynamicLight') ) continue;
+				if ( (a is 'Inventory') && Inventory(a).Owner ) continue;
+				if ( (a is 'SWWMPickupFlash') && (a.CurState == a.FindState('Pickup')) ) continue;
+				if ( (a is 'SWWMShadow') || (a is 'SWWMItemOverlay') || (a is 'HeadpatTracker') || (a is 'SWWMTeleportLine') || (a is 'SWWMTeleportDest') ) continue;
+				if ( a.Distance3DSquared(e.Camera) > 1000000 ) continue;
+				DrawActor(e,a);
+			}
 		}
 	}
 }
diff --git a/zscript/handler/swwm_handler_worldload.zsc b/zscript/handler/swwm_handler_worldload.zsc
index be0debd4a..203bac29b 100644
--- a/zscript/handler/swwm_handler_worldload.zsc
+++ b/zscript/handler/swwm_handler_worldload.zsc
@@ -17,10 +17,42 @@ Class RampancyLogonDummy : Actor
 	}
 }
 
+// this is used to speed up iteration through sector thinglists within a specific area
+Class SectorBounds
+{
+	Vector4 bounds;
+	int portalgroup;
+
+	clearscope bool PointInSectorBounds( Vector2 p, int pg = -1 ) const
+	{
+		if ( (pg >= 0) && (level.GetPortalGroupCount() > 0) && (pg != portalgroup) )
+			p += level.GetDisplacement(pg,portalgroup);
+		if ( p.x < bounds.x ) return false;
+		if ( p.y < bounds.y ) return false;
+		if ( p.x > bounds.z ) return false;
+		if ( p.y > bounds.w ) return false;
+		return true;
+	}
+
+	clearscope bool BoxInSectorBounds( Vector2 p, double r, int pg = -1 ) const
+	{
+		if ( (pg >= 0) && (level.GetPortalGroupCount() > 0) && (pg != portalgroup) )
+			p += level.GetDisplacement(pg,portalgroup);
+		if ( p.x+r < bounds.x ) return false;
+		if ( p.y+r < bounds.y ) return false;
+		if ( p.x-r > bounds.z ) return false;
+		if ( p.y-r > bounds.w ) return false;
+		return true;
+	}
+}
+
 extend Class SWWMHandler
 {
 	bool maphaskeys;
 
+	// weird optimization
+	Array<SectorBounds> sbounds;
+
 	// level end stats
 	override void WorldUnloaded( WorldEvent e )
 	{
@@ -146,6 +178,51 @@ extend Class SWWMHandler
 			SWWMUtility.MarkAchievement("hurry",players[consoleplayer]);
 	}
 
+	clearscope bool PointInSectorBounds( Sector s, Vector2 p, int pg = -1 ) const
+	{
+		if ( sbounds.Size() <= 0 ) return false;
+		int i = s.Index();
+		return sbounds[i].PointInSectorBounds(p,pg);
+	}
+
+	clearscope bool BoxInSectorBounds( Sector s, Vector2 p, double r, int pg = -1 ) const
+	{
+		if ( sbounds.Size() <= 0 ) return false;
+		int i = s.Index();
+		return sbounds[i].BoxInSectorBounds(p,r,pg);
+	}
+
+	void PrecalculateSectorBounds()
+	{
+		sbounds.Resize(level.Sectors.Size());
+		foreach ( s:level.Sectors )
+		{
+			let sb = new("SectorBounds");
+			sb.portalgroup = s.portalgroup;
+			sb.bounds = ( 32767, 32767, -32768, -32768 );
+			foreach ( l:s.Lines )
+			{
+				if ( l.v1.p.x < sb.bounds.x )
+					sb.bounds.x = l.v1.p.x;
+				if ( l.v2.p.x < sb.bounds.x )
+					sb.bounds.x = l.v2.p.x;
+				if ( l.v1.p.y < sb.bounds.y )
+					sb.bounds.y = l.v1.p.y;
+				if ( l.v2.p.y < sb.bounds.y )
+					sb.bounds.y = l.v2.p.y;
+				if ( l.v1.p.x > sb.bounds.z )
+					sb.bounds.z = l.v1.p.x;
+				if ( l.v2.p.x > sb.bounds.z )
+					sb.bounds.z = l.v2.p.x;
+				if ( l.v1.p.y > sb.bounds.w )
+					sb.bounds.w = l.v1.p.y;
+				if ( l.v2.p.y > sb.bounds.w )
+					sb.bounds.w = l.v2.p.y;
+			}
+			sbounds[s.Index()] = sb;
+		}
+	}
+
 	private void MapStartDialogues()
 	{
 		int whichboss = WhichVanillaBossMap();
@@ -264,6 +341,7 @@ extend Class SWWMHandler
 		// (if we do it in OnRegister the existing thinker might not have been deserialized yet)
 		gdat = SWWMGlobals.Get();
 		if ( e.IsReopen ) return;
+		PrecalculateSectorBounds();
 		MapStartDialogues();
 		if ( gamestate != GS_TITLELEVEL )
 		{
diff --git a/zscript/handler/swwm_handler_worldthings.zsc b/zscript/handler/swwm_handler_worldthings.zsc
index 5bcbdd6ac..9fb85b456 100644
--- a/zscript/handler/swwm_handler_worldthings.zsc
+++ b/zscript/handler/swwm_handler_worldthings.zsc
@@ -172,18 +172,12 @@ extend Class SWWMHandler
 	// copies the floatbob of overlapping identical items, so it doesn't look weird
 	private void CopyFloatBob( Actor a )
 	{
-		bool breakout = false;
-		foreach ( s:level.Sectors )
+		for ( Actor t=a.CurSector.thinglist; t; t=t.snext )
 		{
-			for ( Actor t=s.thinglist; t; t=t.snext )
-			{
-				if ( (t == a) || !(t is 'Inventory') || !(t.spawnpoint ~== a.spawnpoint) ) continue;
-				a.floatbobphase = t.floatbobphase;
-				a.angle = t.angle;	// also copy angle
-				breakout = true;
-				break;
-			}
-			if ( breakout ) break;
+			if ( (t == a) || !(t is 'Inventory') || !(t.spawnpoint ~== a.spawnpoint) ) continue;
+			a.floatbobphase = t.floatbobphase;
+			a.angle = t.angle;	// also copy angle
+			break;
 		}
 	}
 
diff --git a/zscript/handler/swwm_handler_worldtick.zsc b/zscript/handler/swwm_handler_worldtick.zsc
index dcec0adfc..37ec33e1f 100644
--- a/zscript/handler/swwm_handler_worldtick.zsc
+++ b/zscript/handler/swwm_handler_worldtick.zsc
@@ -281,42 +281,48 @@ extend Class SWWMHandler
 		double viewdist = SWWMStatusBar.MAPVIEWDIST;
 		// still about as expensive as using a BlockThingsIterator, but without the need to allocate one every tic
 		int thisgroup = players[consoleplayer].Camera.CurSector.portalgroup;
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		foreach ( s:level.Sectors )
 		{
-			Vector2 rv;
-			if ( s.portalgroup != thisgroup )
+			// don't check sectors that aren't within bounds, saves some time
+			if ( !BoxInSectorBounds(s,players[consoleplayer].Camera.pos.xy,viewdist,players[consoleplayer].Camera.CurSector.PortalGroup) )
+				continue;
+			for ( Actor a=s.thinglist; a; a=a.snext )
 			{
-				Vector2 relpos = players[consoleplayer].Camera.pos.xy+level.GetDisplacement(thisgroup,s.portalgroup);
-				rv = a.pos.xy-relpos;
+				Vector2 rv;
+				if ( s.portalgroup != thisgroup )
+				{
+					Vector2 relpos = players[consoleplayer].Camera.pos.xy+level.GetDisplacement(thisgroup,s.portalgroup);
+					rv = a.pos.xy-relpos;
+				}
+				else rv = a.pos.xy-players[consoleplayer].Camera.pos.xy;
+				double rad;
+				bool isproj = a.bMISSILE&&SWWMUtility.ValidProjectile(a);
+				if ( SWWMUtility.IsBeamProj(a) )
+				{
+					isproj = true;
+					rad = SWWMUtility.IsYBeam(a)?(a.scale.y*cos(a.pitch-90)):(a.speed*cos(a.pitch));
+				}
+				else rad = a.radius;
+				if ( max(abs(rv.x)-a.radius,abs(rv.y)-a.radius) > viewdist )
+					continue;
+				if ( a == players[consoleplayer].Camera )
+					continue;
+				if ( a is 'GhostTarget' )
+					continue;
+				if ( !a.player && !a.bSOLID && !a.bSHOOTABLE && !a.bISMONSTER && !a.bFRIENDLY && !(a is 'Inventory') && !(a is 'Chancebox') && !isproj )
+					continue;
+				if ( !level.allmap && !(deathmatch && (a is 'Inventory') && !a.bDROPPED) && !(a.IsFriend(players[consoleplayer].mo) && !(a.player && (a.player.mo != a))) && !a.CheckSight(players[consoleplayer].Camera,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
+					continue;
+				if ( a.bKILLED || (a.Health <= 0) || a.bUnmorphed )
+					continue;
+				if ( (a is 'Inventory') && (!a.bSPECIAL || Inventory(a).Owner || (a.GetClassName() == 'aas_token')) )	// autoautosave hotfix
+					continue;
+				if ( (a is 'Chancebox') && (a.CurState != a.SpawnState) )
+					continue;
+				if ( isproj && !level.allmap && !(a.target && a.target.IsFriend(players[consoleplayer].mo)) && !a.CheckSight(players[consoleplayer].Camera,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
+					continue;
+				SWWMSimpleTracker.Track(self,a);
 			}
-			else rv = a.pos.xy-players[consoleplayer].Camera.pos.xy;
-			double rad;
-			bool isproj = a.bMISSILE&&SWWMUtility.ValidProjectile(a);
-			if ( SWWMUtility.IsBeamProj(a) )
-			{
-				isproj = true;
-				rad = SWWMUtility.IsYBeam(a)?(a.scale.y*cos(a.pitch-90)):(a.speed*cos(a.pitch));
-			}
-			else rad = a.radius;
-			if ( max(abs(rv.x)-a.radius,abs(rv.y)-a.radius) > viewdist )
-				continue;
-			if ( a == players[consoleplayer].Camera )
-				continue;
-			if ( a is 'GhostTarget' )
-				continue;
-			if ( !a.player && !a.bSOLID && !a.bSHOOTABLE && !a.bISMONSTER && !a.bFRIENDLY && !(a is 'Inventory') && !(a is 'Chancebox') && !isproj )
-				continue;
-			if ( !level.allmap && !(deathmatch && (a is 'Inventory') && !a.bDROPPED) && !(a.IsFriend(players[consoleplayer].mo) && !(a.player && (a.player.mo != a))) && !a.CheckSight(players[consoleplayer].Camera,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
-				continue;
-			if ( a.bKILLED || (a.Health <= 0) || a.bUnmorphed )
-				continue;
-			if ( (a is 'Inventory') && (!a.bSPECIAL || Inventory(a).Owner || (a.GetClassName() == 'aas_token')) )	// autoautosave hotfix
-				continue;
-			if ( (a is 'Chancebox') && (a.CurState != a.SpawnState) )
-				continue;
-			if ( isproj && !level.allmap && !(a.target && a.target.IsFriend(players[consoleplayer].mo)) && !a.CheckSight(players[consoleplayer].Camera,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
-				continue;
-			SWWMSimpleTracker.Track(self,a);
 		}
 		SWWMSimpleTracker trk = strackers;
 		SWWMSimpleTracker prev = null, next;
diff --git a/zscript/handler/swwm_statichandler.zsc b/zscript/handler/swwm_statichandler.zsc
index 1c863600f..f1fe9a992 100644
--- a/zscript/handler/swwm_statichandler.zsc
+++ b/zscript/handler/swwm_statichandler.zsc
@@ -99,6 +99,10 @@ Class SWWMStaticHandler : StaticEventHandler
 		SWWMHandler.ClearAllShaders();
 		EventHandler.SendInterfaceEvent(consoleplayer,"swwmflushhud");
 		EventHandler.SendInterfaceEvent(consoleplayer,"swwmaprcheck");
+		// quick fix for old savegames
+		let hnd = SWWMHandler(EventHandler.Find("SWWMHandler"));
+		if ( hnd && (hnd.sbounds.Size() <= 0) )
+			hnd.PrecalculateSectorBounds();
 		if ( !e.IsSaveGame ) return;
 		// save version checker
 		tainted = false;
diff --git a/zscript/items/swwm_ammoextra.zsc b/zscript/items/swwm_ammoextra.zsc
index f45f5e642..4cf174fd3 100644
--- a/zscript/items/swwm_ammoextra.zsc
+++ b/zscript/items/swwm_ammoextra.zsc
@@ -524,7 +524,7 @@ Class HammerspaceEmbiggener : Inventory
 		if ( gameinfo.gametype&GAME_DoomChex )
 			A_SetSize(-1,26);
 		int tamount = Amount;
-		foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; )
+		for ( Actor t=CurSector.thinglist; t; )
 		{
 			let next = t.snext;
 			if ( (t == self) || !(t is 'HammerspaceEmbiggener') || !(t.spawnpoint ~== spawnpoint) )
diff --git a/zscript/items/swwm_lamp.zsc b/zscript/items/swwm_lamp.zsc
index d46d9d815..9546fee6a 100644
--- a/zscript/items/swwm_lamp.zsc
+++ b/zscript/items/swwm_lamp.zsc
@@ -5,6 +5,7 @@ Class LampMoth : Actor
 	Actor lamp;
 	Vector3 trail, ofs;
 	int lifespan;
+	SWWMHandler hnd;
 
 	Default
 	{
@@ -59,18 +60,25 @@ Class LampMoth : Actor
 		{
 			// look for nearby lamps
 			double mindist = 62500.;
-			foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+			if ( !hnd ) SWWMHandler(EventHandler.Find("SWWMHandler"));
+			foreach ( s:level.Sectors )
 			{
-				if ( !(a is 'CompanionLamp') ) continue;
-				double dist = Distance3DSquared(a);
-				if ( (a.frame == 0) || (dist > mindist) && !CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
-				mindist = dist;
-				lamp = a;
-				master = a.target;
-				if ( CompanionLamp(lamp).moff.Find(self) == CompanionLamp(lamp).moff.Size() )
-					CompanionLamp(lamp).moff.Push(self);
-				if ( master && master.player ) SetFriendPlayer(master.player);
-				else bFRIENDLY = false;
+				// don't check sectors that aren't within bounds, saves some time
+				if ( !hnd.BoxInSectorBounds(s,pos.xy,250,CurSector.PortalGroup) )
+					continue;
+				for ( Actor a=s.thinglist; a; a=a.snext )
+				{
+					if ( !(a is 'CompanionLamp') ) continue;
+					double dist = Distance3DSquared(a);
+					if ( (a.frame == 0) || (dist > mindist) && !CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+					mindist = dist;
+					lamp = a;
+					master = a.target;
+					if ( CompanionLamp(lamp).moff.Find(self) == CompanionLamp(lamp).moff.Size() )
+						CompanionLamp(lamp).moff.Push(self);
+					if ( master && master.player ) SetFriendPlayer(master.player);
+					else bFRIENDLY = false;
+				}
 			}
 		}
 		if ( !lamp || (lamp.frame == 0) || (Distance3DSquared(lamp) > 62500) || !CheckSight(lamp,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) return false;
diff --git a/zscript/items/swwm_powerups.zsc b/zscript/items/swwm_powerups.zsc
index 36fb945ac..a35ae6846 100644
--- a/zscript/items/swwm_powerups.zsc
+++ b/zscript/items/swwm_powerups.zsc
@@ -310,9 +310,11 @@ Class GhostTarget : Actor
 		}
 		if ( isFrozen() ) return;
 		if ( diedie ) A_FadeOut(.05);
-		foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+		let bt = BlockThingsIterator.Create(self,256);
+		while ( bt.Next() )
 		{
-			if ( !t.bIsMonster || t.player || !t.IsHostile(master) || (t.target != self) ) continue;
+			let t = bt.Thing;
+			if ( !t || !t.bIsMonster || t.player || !t.IsHostile(master) || (t.target != self) ) continue;
 			if ( SWWMUtility.BoxIntersect(self,t,pad:16) || t.CheckMeleeRange() )
 			{
 				// they found out, there's no one here
@@ -320,9 +322,11 @@ Class GhostTarget : Actor
 				break;
 			}
 		}
+		bt.Destroy();
 		// player made noise or is visible again
 		if ( !master || (LastHeard == master) || !master.FindInventory("GhostPower") )
 		{
+			// note: this is faster than using a thinkeriterator
 			foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
 			{
 				if ( !a.bISMONSTER || a.player || !a.IsHostile(master) || (a.Health <= 0) ) continue;
diff --git a/zscript/items/swwm_powerups_vip.zsc b/zscript/items/swwm_powerups_vip.zsc
index b83ab388f..cf47d4738 100644
--- a/zscript/items/swwm_powerups_vip.zsc
+++ b/zscript/items/swwm_powerups_vip.zsc
@@ -510,18 +510,27 @@ Class Mykradvo : Inventory
 	{
 		targets.Clear();
 		// search all actively hostile enemies within 50m
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		BlockThingsIterator bt;
+		for ( int i=0; i<level.GetPortalGroupCount(); i++ )
 		{
-			// must be an active, shootable live monster
-			if ( !a.bISMONSTER || !a.bSHOOTABLE || a.bDORMANT || (a.Health <= 0) ) continue;
-			// skip non-hostiles
-			if ( a.IsFriend(t) ) continue;
-			// is targetting us and is within 10m
-			// or
-			// is visible and is within 100m
-			if ( ((a.target == t) && SWWMUtility.SphereIntersect(a,t.pos,320))
-				|| (t.CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) && SWWMUtility.SphereIntersect(a,t.pos,3200)) )
-				targets.Push(a);
+			Vector2 disp = level.GetDisplacement(t.CurSector.PortalGroup,i);
+			bt = BlockThingsIterator.CreateFromPos(t.pos.x+disp.x,t.pos.y+disp.y,t.pos.z,3200,3200,false);
+			while ( bt.Next() )
+			{
+				let a = bt.Thing;
+				// must be an active, shootable live monster
+				if ( !a || !a.bISMONSTER || !a.bSHOOTABLE || a.bDORMANT || (a.Health <= 0) ) continue;
+				// skip non-hostiles
+				if ( a.IsFriend(t) ) continue;
+				// is targetting us and is within 10m
+				// or
+				// is visible and is within 100m
+				if ( !((a.target == t) && SWWMUtility.SphereIntersect(a,t.pos,320))
+					&& !(t.CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) && SWWMUtility.SphereIntersect(a,t.pos,3200)) ) continue;
+				if ( targets.Find(a) >= targets.Size() )
+					targets.Push(a);
+			}
+			bt.Destroy();
 		}
 		// sorted, so the closest take priority
 		qsort_targets(targets,0,targets.Size()-1,t);
diff --git a/zscript/player/swwm_player_tick.zsc b/zscript/player/swwm_player_tick.zsc
index 73e288ec5..1b4d710b9 100644
--- a/zscript/player/swwm_player_tick.zsc
+++ b/zscript/player/swwm_player_tick.zsc
@@ -5,8 +5,11 @@ extend Class Demolitionist
 	{
 		if ( player.cmd.buttons&BT_USER3 )
 		{
-			foreach ( s:level.Sectors ) for ( Actor i=s.thinglist; i; i=i.snext )
+			let bt = BlockThingsIterator.Create(self,800);
+			while ( bt.Next() )
 			{
+				let i = bt.Thing;
+				if ( !i ) continue;
 				if ( !(i is 'Inventory') && !(i is 'Chancebox') && !(i is 'SWWMRespawnTimer') ) continue;
 				if ( (i is 'Inventory') && (i.bINVISIBLE || !i.bSPECIAL || Inventory(i).Owner) ) continue;
 				if ( (i is 'Chancebox') && (i.CurState != i.SpawnState) ) continue;
@@ -14,6 +17,7 @@ extend Class Demolitionist
 				if ( !level.allmap && !i.CheckSight(self,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
 				SWWMItemSense.Spawn(self,i);
 			}
+			bt.Destroy();
 		}
 		SWWMItemsense itm = itemsense;
 		SWWMItemsense prev = null, next;
@@ -50,8 +54,11 @@ extend Class Demolitionist
 			}
 			if ( (magitem_cnt < 8) && !swwm_usetopickup )
 			{
-				foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+				let bt = BlockThingsIterator.Create(self,500);
+				while ( bt.Next() )
 				{
+					let t = bt.Thing;
+					if ( !t ) continue;
 					if ( !(t is 'Inventory') || !t.bSPECIAL || !t.bDROPPED || t.bINVISIBLE || Inventory(t).Owner || !SWWMUtility.SphereIntersect(t,pos,500) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
 						continue;
 					let i = Inventory(t);
@@ -82,6 +89,7 @@ extend Class Demolitionist
 					magitem = nmi;
 					magitem_cnt++;
 				}
+				bt.Destroy();
 			}
 			SWWMMagItem itm = magitem;
 			SWWMMagItem prev = null, next;
@@ -548,12 +556,12 @@ extend Class Demolitionist
 			let raging = RagekitPower(FindInventory("RagekitPower"));
 			double maxmass = max(mass*spd/40.,200);
 			if ( raging ) maxmass *= 2;
-			Array<Actor> hitlist;
-			hitlist.Clear();
-			// gather first
-			foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+			let bt = BlockThingsIterator.Create(self,spd+radius+1024);
+			while ( bt.Next() )
 			{
-				if ( (a == self) || (!a.bSOLID && !a.bSHOOTABLE) || a.bTHRUACTORS || a.bCORPSE || !CanCollideWith(a,false) || !a.CanCollideWith(self,true) ) continue;
+				if ( spd <= 0 ) break;	// if something stopped us, no more iteration
+				let a = bt.Thing;
+				if ( !a || (a == self) || (!a.bSOLID && !a.bSHOOTABLE) || a.bTHRUACTORS || a.bCORPSE || !CanCollideWith(a,false) || !a.CanCollideWith(self,true) ) continue;
 				if ( !SWWMUtility.ExtrudeIntersect(self,a,dir*(spd+radius),8) ) continue;
 				if ( (a.pos.z <= a.floorz) && (a.height <= MaxStepHeight) ) continue;
 				Vector3 diff = level.Vec3Diff(pos,a.pos);
@@ -574,15 +582,6 @@ extend Class Demolitionist
 					if ( dir dot bnorm > -.6 ) continue;
 				}
 				if ( !CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
-				hitlist.Push(a);
-			}
-			foreach ( a:hitlist )
-			{
-				if ( !a ) continue;
-				if ( spd <= 0 ) break;
-				// we have to recalculate these
-				Vector3 diff = level.Vec3Diff(pos,a.pos);
-				Vector3 dirto = diff.unit();
 				// large monsters will stop the player (unless hit from above if we're going at ground pound speed)
 				A_QuakeEx(4.,4.,4.,10,0,128,"",QF_RELATIVE|QF_SCALEDOWN|QF_3D);
 				A_AlertMonsters(swwm_uncapalert?0:800);
@@ -647,6 +646,7 @@ extend Class Demolitionist
 					raging.DoHitFX();
 				}
 			}
+			bt.Destroy();
 			// check for ceiling collision
 			if ( (spd > 0) && !bumped && ((pos.z+Height+dir.z*spd) >= ceilingz) )
 			{
diff --git a/zscript/utility/swwm_utility_blast.zsc b/zscript/utility/swwm_utility_blast.zsc
index 58e1dfd52..37bf24feb 100644
--- a/zscript/utility/swwm_utility_blast.zsc
+++ b/zscript/utility/swwm_utility_blast.zsc
@@ -68,30 +68,42 @@ extend Class SWWMUtility
 		Array<Actor> hitlist;
 		hitlist.Clear();
 		// gather first
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		BlockThingsIterator bt;
+		int thisgroup = Source.CurSector.PortalGroup;
+		// we need to check all possible portal groups due to quirks of blockthingsiterator and sector portals
+		for ( int i=0; i<level.GetPortalGroupCount(); i++ )
 		{
-			// early checks for self and ignored actor (usually the instigator)
-			if ( (a == ignoreme) || (a == Source) )
-				continue;
-			// can't be affected
-			if ( !a.bSHOOTABLE && !a.bVULNERABLE )
-				continue;
-			// no blasting if no radius dmg (unless forced)
-			if ( a.bNORADIUSDMG && !Source.bFORCERADIUSDMG )
-				continue;
-			// check the DONTHARMCLASS/DONTHARMSPECIES flags
-			if ( !a.player && ((Source.bDONTHARMCLASS && (a.GetClass() == Source.GetClass())) || (Source.bDONTHARMSPECIES && (a.GetSpecies() == Source.GetSpecies()))) )
-				continue;
-			// check friendliness
-			if ( (flags&DE_NOHURTFRIEND) && Instigator && Instigator.IsFriend(a) )
-				continue;
-			// can we see it
-			if ( !(flags&DE_THRUWALLS) && !Source.CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
-				continue;
-			// intersecting?
-			if ( !SphereIntersect(a,Source.pos,ExplosionRadius) )
-				continue;
-			hitlist.Push(a);
+			Vector2 disp = level.GetDisplacement(thisgroup,i);
+			bt = BlockThingsIterator.CreateFromPos(Source.pos.x+disp.x,Source.pos.y+disp.y,Source.pos.z,ExplosionRadius,ExplosionRadius,false);
+			while ( bt.Next() )
+			{
+				let a = bt.Thing;
+				// early checks for self and ignored actor (usually the instigator)
+				if ( (a == ignoreme) || (a == Source) )
+					continue;
+				// can't be affected
+				if ( !a.bSHOOTABLE && !a.bVULNERABLE )
+					continue;
+				// no blasting if no radius dmg (unless forced)
+				if ( a.bNORADIUSDMG && !Source.bFORCERADIUSDMG )
+					continue;
+				// check the DONTHARMCLASS/DONTHARMSPECIES flags
+				if ( !a.player && ((Source.bDONTHARMCLASS && (a.GetClass() == Source.GetClass())) || (Source.bDONTHARMSPECIES && (a.GetSpecies() == Source.GetSpecies()))) )
+					continue;
+				// check friendliness
+				if ( (flags&DE_NOHURTFRIEND) && Instigator && Instigator.IsFriend(a) )
+					continue;
+				// can we see it
+				if ( !(flags&DE_THRUWALLS) && !Source.CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
+					continue;
+				// intersecting?
+				if ( !SphereIntersect(a,Source.pos,ExplosionRadius) )
+					continue;
+				// add it if not already on list
+				if ( hitlist.Find(a) >= hitlist.Size() )
+					hitlist.Push(a);
+			}
+			bt.Destroy();
 		}
 		foreach ( a:hitlist )
 		{
diff --git a/zscript/weapons/swwm_baseweapon_melee.zsc b/zscript/weapons/swwm_baseweapon_melee.zsc
index 6ef9ddcf1..71e2357f2 100644
--- a/zscript/weapons/swwm_baseweapon_melee.zsc
+++ b/zscript/weapons/swwm_baseweapon_melee.zsc
@@ -101,6 +101,7 @@ Class ParryField : SWWMNonInteractiveActor
 {
 	bool critsnd;
 	Array<Actor> justparried;
+	SWWMHandler hnd;
 
 	override void Tick()
 	{
@@ -113,78 +114,85 @@ Class ParryField : SWWMNonInteractiveActor
 		let raging = RagekitPower(master.FindInventory("RagekitPower"));
 		let st = Demolitionist(master).mystats;
 		// check for projectiles to deflect
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		if ( !hnd ) hnd = SWWMHandler(EventHandler.Find("SWWMHandler"));
+		foreach ( s:level.Sectors )
 		{
-			if ( (justparried.Find(a) < justparried.Size()) || !(SWWMUtility.ValidProjectile(a) || a.bSKULLFLY) || a.bTHRUACTORS || (level.Vec3Diff(a.pos,pos).length() > 80) ) continue;
-			if ( a is 'Whirlwind' ) SWWMUtility.MarkAchievement("tornado",master.player);
-			justparried.Push(a);
-			Vector3 vdir = a.vel;
-			Vector3 dir = level.Vec3Diff(master.Vec2OffsetZ(0,0,pos.z),a.pos).unit();
-			Vector3 hdir = dir;
-			Actor oldtarget = a.target;
-			if ( (a.target != master) && (a.bMISSILE || (a is 'HolySpirit')) )	// special wraithverge handling
+			// don't check sectors that aren't within bounds, saves some time
+			if ( !hnd.BoxInSectorBounds(s,pos.xy,80,CurSector.PortalGroup) )
+				continue;
+			for ( Actor a=s.thinglist; a; a=a.snext )
 			{
-				// deflect directly to target
-				if ( a.target )
+				if ( (justparried.Find(a) < justparried.Size()) || !(SWWMUtility.ValidProjectile(a) || a.bSKULLFLY) || a.bTHRUACTORS || (level.Vec3Diff(a.pos,pos).length() > 80) ) continue;
+				if ( a is 'Whirlwind' ) SWWMUtility.MarkAchievement("tornado",master.player);
+				justparried.Push(a);
+				Vector3 vdir = a.vel;
+				Vector3 dir = level.Vec3Diff(master.Vec2OffsetZ(0,0,pos.z),a.pos).unit();
+				Vector3 hdir = dir;
+				Actor oldtarget = a.target;
+				if ( (a.target != master) && (a.bMISSILE || (a is 'HolySpirit')) )	// special wraithverge handling
 				{
-					hdir = level.Vec3Diff(a.pos,a.target.Vec3Offset(0,0,a.target.height/2)).unit();
-					double theta = max(FRandom[Parry](0.,1.)**2.,.1);
-					dir = SWWMUtility.LerpVector3(dir,hdir,theta);
+					// deflect directly to target
+					if ( a.target )
+					{
+						hdir = level.Vec3Diff(a.pos,a.target.Vec3Offset(0,0,a.target.height/2)).unit();
+						double theta = max(FRandom[Parry](0.,1.)**2.,.1);
+						dir = SWWMUtility.LerpVector3(dir,hdir,theta);
+					}
+					// push away
+					if ( a.bSEEKERMISSILE ) a.tracer = a.target;
+					a.target = master;
+				}
+				if ( a.bSKULLFLY ) a.bBLASTED = true; // blast lost souls
+				let buff = a.FindInventory("ParriedBuff");
+				if ( !buff )
+				{
+					buff = Inventory(Spawn("ParriedBuff"));
+					buff.AttachToOwner(a);
+					buff.tracer = oldtarget;
+				}
+				double mvel = a.vel.length();
+				double nspeed = min(100,mvel*FRandom[Parry](1.2,1.4)+20);
+				a.angle = atan2(dir.y,dir.x);
+				a.pitch = asin(-dir.z);
+				if ( raging )
+				{
+					buff.special1 |= 2;
+					nspeed = min(100,nspeed*2.);
+					raging.DoHitFX();
 				}
-				// push away
-				if ( a.bSEEKERMISSILE ) a.tracer = a.target;
-				a.target = master;
-			}
-			if ( a.bSKULLFLY ) a.bBLASTED = true; // blast lost souls
-			let buff = a.FindInventory("ParriedBuff");
-			if ( !buff )
-			{
-				buff = Inventory(Spawn("ParriedBuff"));
-				buff.AttachToOwner(a);
-				buff.tracer = oldtarget;
-			}
-			double mvel = a.vel.length();
-			double nspeed = min(100,mvel*FRandom[Parry](1.2,1.4)+20);
-			a.angle = atan2(dir.y,dir.x);
-			a.pitch = asin(-dir.z);
-			if ( raging )
-			{
-				buff.special1 |= 2;
-				nspeed = min(100,nspeed*2.);
-				raging.DoHitFX();
-			}
-			a.vel = dir*nspeed;
-			if ( a.bMISSILE ) a.speed = nspeed;
-			let i = Spawn(raging?"BigPunchImpact":"PunchImpact",a.pos);
-			i.target = master;
-			i.angle = atan2(dir.y,dir.x);
-			i.pitch = asin(-dir.z);
-			i.bAMBUSH = true;
-			A_QuakeEx(3.,3.,3.,10,0,64,"",QF_RELATIVE|QF_SCALEDOWN|QF_3D,rollIntensity:.2);
-			A_StartSound("demolitionist/parry",CHAN_WEAPON);
-			if ( special1 >= special2 )	// perfect parry
-			{
-				// increased homing
-				dir = dir*.4+hdir*.6;
-				nspeed = min(100,nspeed*1.5);
 				a.vel = dir*nspeed;
-				for ( int i=1; i<6; i++ )
+				if ( a.bMISSILE ) a.speed = nspeed;
+				let i = Spawn(raging?"BigPunchImpact":"PunchImpact",a.pos);
+				i.target = master;
+				i.angle = atan2(dir.y,dir.x);
+				i.pitch = asin(-dir.z);
+				i.bAMBUSH = true;
+				A_QuakeEx(3.,3.,3.,10,0,64,"",QF_RELATIVE|QF_SCALEDOWN|QF_3D,rollIntensity:.2);
+				A_StartSound("demolitionist/parry",CHAN_WEAPON);
+				if ( special1 >= special2 )	// perfect parry
 				{
-					let r = Spawn("ParryRing",a.pos);
-					r.specialf1 = i*.04;
+					// increased homing
+					dir = dir*.4+hdir*.6;
+					nspeed = min(100,nspeed*1.5);
+					a.vel = dir*nspeed;
+					for ( int i=1; i<6; i++ )
+					{
+						let r = Spawn("ParryRing",a.pos);
+						r.specialf1 = i*.04;
+					}
+					buff.special1 |= 1;
+					if ( !critsnd )
+					{
+						A_StartSound("misc/soulsparry",CHAN_ITEM,CHANF_OVERLAP,1.,.5);
+						if ( st ) st.pparries++;
+					}
+					critsnd = true;
+					if ( (a is 'LostSoul') && (master.player.ReadyWeapon is 'SilverBullet') )
+						SWWMUtility.MarkAchievement("baseball",master.player);
 				}
-				buff.special1 |= 1;
-				if ( !critsnd )
-				{
-					A_StartSound("misc/soulsparry",CHAN_ITEM,CHANF_OVERLAP,1.,.5);
-					if ( st ) st.pparries++;
-				}
-				critsnd = true;
-				if ( (a is 'LostSoul') && (master.player.ReadyWeapon is 'SilverBullet') )
-					SWWMUtility.MarkAchievement("baseball",master.player);
+				if ( st ) st.parries++;
+				SWWMUtility.AchievementProgressInc("parry",1,master.player);
 			}
-			if ( st ) st.parries++;
-			SWWMUtility.AchievementProgressInc("parry",1,master.player);
 		}
 		if ( --special1 <= 0 ) Destroy();
 	}
diff --git a/zscript/weapons/swwm_blazeit_fx.zsc b/zscript/weapons/swwm_blazeit_fx.zsc
index 396ad167c..ee9490fc6 100644
--- a/zscript/weapons/swwm_blazeit_fx.zsc
+++ b/zscript/weapons/swwm_blazeit_fx.zsc
@@ -266,19 +266,16 @@ Class HellblazerMissile : Actor
 			return;
 		}
 		// proximity check
-		bool checked = false;
-		foreach ( s:level.Sectors )
+		let bt = BlockThingsIterator.Create(self,256);
+		while ( bt.Next() )
 		{
-			for ( Actor t=s.thinglist; t; t=t.snext )
-			{
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),bNOGRAVITY?50:90) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
-				deto++;
-				tracer = t;
-				checked = true;
-				break;
-			}
-			if ( checked ) break;
+			let t = bt.Thing;
+			if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),bNOGRAVITY?50:90) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+			deto++;
+			tracer = t;
+			break;
 		}
+		bt.Destroy();
 	}
 
 	void A_BlazerMissileExplode()
diff --git a/zscript/weapons/swwm_deathlydeathcannon_altfx.zsc b/zscript/weapons/swwm_deathlydeathcannon_altfx.zsc
index a9c7327aa..9752e5119 100644
--- a/zscript/weapons/swwm_deathlydeathcannon_altfx.zsc
+++ b/zscript/weapons/swwm_deathlydeathcannon_altfx.zsc
@@ -952,6 +952,8 @@ Class YnykronSingularity : SWWMNonInteractiveActor
 
 	transient SimpleMoveTracer mt;
 
+	SWWMHandler hnd;
+
 	override void PostBeginPlay()
 	{
 		let g = Spawn("YnykronHalo",pos);
@@ -1083,19 +1085,26 @@ Class YnykronSingularity : SWWMNonInteractiveActor
 		Array<Actor> candidates;
 		candidates.Clear();
 		// gather first
-		foreach ( s:level.Sectors ) for ( Actor a=s.thinglist; a; a=a.snext )
+		if ( !hnd ) hnd = SWWMHandler(EventHandler.Find("SWWMHandler"));
+		foreach ( s:level.Sectors )
 		{
-			if ( !a.bSHOOTABLE && !(a is 'Inventory') && !SWWMUtility.ValidProjectile(a) )
+			// don't check sectors that aren't within bounds, saves some time
+			if ( !hnd.BoxInSectorBounds(s,pos.xy,20000.*scale.x,CurSector.PortalGroup) )
 				continue;
-			if ( a.bDORMANT || (a.Health <= 0) || (a == self) || !SWWMUtility.SphereIntersect(a,pos,20000.*scale.x) || !CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
-				continue;
-			if ( (a is 'Inventory') && !a.bDROPPED )	// must be a dropped pickup
-				continue;
-			if ( a.player && (a.player.cheats&CF_NOCLIP2) )	// for safety
-				continue;
-			if ( (a is 'YnykronSingularity') && a.bNOBLOCKMAP )	// dead singularity, ignore
-				continue;
-			candidates.Push(a);
+			for ( Actor a=s.thinglist; a; a=a.snext )
+			{
+				if ( !a.bSHOOTABLE && !(a is 'Inventory') && !SWWMUtility.ValidProjectile(a) )
+					continue;
+				if ( a.bDORMANT || (a.Health <= 0) || (a == self) || !SWWMUtility.SphereIntersect(a,pos,20000.*scale.x) || !CheckSight(a,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
+					continue;
+				if ( (a is 'Inventory') && !a.bDROPPED )	// must be a dropped pickup
+					continue;
+				if ( a.player && (a.player.cheats&CF_NOCLIP2) )	// for safety
+					continue;
+				if ( (a is 'YnykronSingularity') && a.bNOBLOCKMAP )	// dead singularity, ignore
+					continue;
+				candidates.Push(a);
+			}
 		}
 		foreach ( a:candidates )
 		{
diff --git a/zscript/weapons/swwm_deathlydeathcannon_fx.zsc b/zscript/weapons/swwm_deathlydeathcannon_fx.zsc
index a907313b9..6e4464609 100644
--- a/zscript/weapons/swwm_deathlydeathcannon_fx.zsc
+++ b/zscript/weapons/swwm_deathlydeathcannon_fx.zsc
@@ -467,15 +467,25 @@ Class YnykronImpact : SWWMNonInteractiveActor
 		}
 		Array<Actor> candidates;
 		candidates.Clear();
-		foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+		BlockThingsIterator bt;
+		// gather first, making sure to traverse through all portal groups just in case
+		for ( int i=0; i<level.GetPortalGroupCount(); i++ )
 		{
-			if ( !t.bSHOOTABLE || !SWWMUtility.SphereIntersect(t,pos,rad) || (!SWWMUtility.SphereIntersect(t,pos,100) && !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY)) ) continue;
-			if ( YnykronShot(master) && (YnykronShot(master).hitlist.Find(t) < YnykronShot(master).hitlist.Size()) )
-				continue;
-			Vector3 dirto = level.Vec3Diff(pos,t.Vec3Offset(0,0,t.Height/2));
-			double dist = dirto.length();
-			if ( (dist > rad/2) && (t == target) ) continue;
-			candidates.Push(t);
+			Vector2 disp = level.GetDisplacement(CurSector.PortalGroup,i);
+			bt = BlockThingsIterator.CreateFromPos(pos.x+disp.x,pos.y+disp.y,pos.z,rad,rad,false);
+			while ( bt.Next() )
+			{
+				let t = bt.Thing;
+				if ( !t || !t.bSHOOTABLE || !SWWMUtility.SphereIntersect(t,pos,rad) || (!SWWMUtility.SphereIntersect(t,pos,100) && !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY)) ) continue;
+				if ( YnykronShot(master) && (YnykronShot(master).hitlist.Find(t) < YnykronShot(master).hitlist.Size()) )
+					continue;
+				Vector3 dirto = level.Vec3Diff(pos,t.Vec3Offset(0,0,t.Height/2));
+				double dist = dirto.length();
+				if ( (dist > rad/2) && (t == target) ) continue;
+				if ( candidates.Find(t) >= candidates.Size() )
+					candidates.Push(t);
+			}
+			bt.Destroy();
 		}
 		qsort_candidates(candidates,0,candidates.Size()-1);
 		candidates.Resize(2);
diff --git a/zscript/weapons/swwm_deepdarkimpact.zsc b/zscript/weapons/swwm_deepdarkimpact.zsc
index f1726667b..e69c303ec 100644
--- a/zscript/weapons/swwm_deepdarkimpact.zsc
+++ b/zscript/weapons/swwm_deepdarkimpact.zsc
@@ -212,29 +212,36 @@ Class DeepImpact : SWWMWeapon
 			l.a.DamageMobj(p,self,int(dmg/250.),'Push',DMG_THRUSTLESS|DMG_INFLICTOR_IS_PUFF);
 		}
 		let st = Demolitionist(self).mystats;
-		foreach ( s:level.Sectors ) for ( Actor m=s.thinglist; m; m=m.snext )
+		let hnd = SWWMHandler(EventHandler.Find("SWWMHandler"));
+		foreach ( s:level.Sectors )
 		{
-			if ( !SWWMUtility.ValidProjectile(m) ) continue;
-			Vector3 rdir = level.Vec3Diff(origin,m.pos);
-			double rdist = rdir.length();
-			if ( rdist <= 0. ) continue;
-			rdir /= rdist;
-			if ( LineTrace(atan2(rdir.y,rdir.x),rdist,asin(-rdir.z),TRF_THRUACTORS|TRF_ABSPOSITION,origin.z,origin.x,origin.y) || (rdist > 250) || (rdir dot x < .75) ) continue;
-			m.speed = m.vel.length();
-			m.vel = m.speed*1.5*(-m.vel.unit()*.3+rdir+x*.2).unit();
-			Vector3 ndir = m.vel.unit();
-			m.angle = atan2(ndir.y,ndir.x);
-			m.pitch = asin(-ndir.z);
-			if ( m.bSEEKERMISSILE && (m.target != self) ) m.tracer = m.target;
-			m.target = self;
-			if ( !m.FindInventory("ParriedBuff") )
+			// don't check sectors that aren't within bounds, saves some time
+			if ( !hnd.BoxInSectorBounds(s,origin.xy,250,level.PointInSector(origin.xy).PortalGroup) )
+				continue;
+			for ( Actor m=s.thinglist; m; m=m.snext )
 			{
-				let pb = Inventory(Spawn("ParriedBuff"));
-				pb.AttachToOwner(m);
-				pb.bAMBUSH = true;
+				if ( !SWWMUtility.ValidProjectile(m) ) continue;
+				Vector3 rdir = level.Vec3Diff(origin,m.pos);
+				double rdist = rdir.length();
+				if ( rdist <= 0. ) continue;
+				rdir /= rdist;
+				if ( LineTrace(atan2(rdir.y,rdir.x),rdist,asin(-rdir.z),TRF_THRUACTORS|TRF_ABSPOSITION,origin.z,origin.x,origin.y) || (rdist > 250) || (rdir dot x < .75) ) continue;
+				m.speed = m.vel.length();
+				m.vel = m.speed*1.5*(-m.vel.unit()*.3+rdir+x*.2).unit();
+				Vector3 ndir = m.vel.unit();
+				m.angle = atan2(ndir.y,ndir.x);
+				m.pitch = asin(-ndir.z);
+				if ( m.bSEEKERMISSILE && (m.target != self) ) m.tracer = m.target;
+				m.target = self;
+				if ( !m.FindInventory("ParriedBuff") )
+				{
+					let pb = Inventory(Spawn("ParriedBuff"));
+					pb.AttachToOwner(m);
+					pb.bAMBUSH = true;
+				}
+				if ( st ) st.parries++;
+				SWWMUtility.AchievementProgressInc("parry",1,player);
 			}
-			if ( st ) st.parries++;
-			SWWMUtility.AchievementProgressInc("parry",1,player);
 		}
 		int numpt = Random[Impact](7,12);
 		for ( int i=0; i<numpt; i++ )
diff --git a/zscript/weapons/swwm_sparkyboi_fx.zsc b/zscript/weapons/swwm_sparkyboi_fx.zsc
index e6281c427..b6926c0ec 100644
--- a/zscript/weapons/swwm_sparkyboi_fx.zsc
+++ b/zscript/weapons/swwm_sparkyboi_fx.zsc
@@ -192,15 +192,18 @@ Class BigBiospark : Actor
 		if ( !(special2%5) )
 		{
 			double closest = double.infinity;
-			foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+			let bt = BlockThingsIterator.Create(self,8000);
+			while ( bt.Next() )
 			{
+				let t = bt.Thing;
 				double dist;
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 64000000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+				if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 64000000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
 				Vector3 dirto = level.Vec3Diff(pos,t.Vec3Offset(0,0,t.height/2)).unit();
 				if ( dist > closest ) continue;
 				closest = dist;
 				tracer = t;
 			}
+			bt.Destroy();
 		}
 		if ( tracer && (tracer.Health > 0) && CheckSight(tracer,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
 		{
@@ -222,11 +225,20 @@ Class BigBiospark : Actor
 		// deal (proper) radius damage
 		Array<Actor> hitlist;
 		hitlist.Clear();
-		// gather first
-		foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+		// gather first, making sure to traverse through all portal groups just in case
+		BlockThingsIterator bt;
+		for ( int i=0; i<level.GetPortalGroupCount(); i++ )
 		{
-			if ( !t.bSHOOTABLE || !SWWMUtility.SphereIntersect(t,pos,120) ) continue;
-			hitlist.Push(t);
+			Vector2 disp = level.GetDisplacement(CurSector.PortalGroup,i);
+			bt = BlockThingsIterator.CreateFromPos(pos.x+disp.x,pos.y+disp.y,pos.z,120,120,false);
+			while ( bt.Next() )
+			{
+				let t = bt.Thing;
+				if ( !t || !t.bSHOOTABLE || !SWWMUtility.SphereIntersect(t,pos,120) ) continue;
+				if ( hitlist.Find(t) >= hitlist.Size() )
+					hitlist.Push(t);
+			}
+			bt.Destroy();
 		}
 		foreach ( t:hitlist )
 		{
@@ -466,16 +478,19 @@ Class BiosparkBall : Actor
 		if ( !(special2%5) )
 		{
 			double closest = double.infinity;
-			foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+			let bt = BlockThingsIterator.Create(self,8000);
+			while ( bt.Next() )
 			{
+				let t = bt.Thing;
 				double dist;
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+				if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
 				Vector3 dirto = level.Vec3Diff(pos,t.Vec3Offset(0,0,t.height/2)).unit();
 				if ( dir dot dirto < .5 ) continue;	// don't seek stuff that's behind us
 				if ( dist > closest ) continue;
 				closest = dist;
 				tracer = t;
 			}
+			bt.Destroy();
 		}
 		if ( tracer && (tracer.Health > 0) && CheckSight(tracer,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) )
 		{
@@ -496,18 +511,15 @@ Class BiosparkBall : Actor
 			return;
 		}
 		// proximity check
-		bool checked = false;
-		foreach ( s:level.Sectors )
+		let bt = BlockThingsIterator.Create(self,256);
+		while ( bt.Next() )
 		{
-			for ( Actor t=s.thinglist; t; t=t.snext )
-			{
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain')) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),16) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
-				deto++;
-				checked = true;
-				break;
-			}
-			if ( checked ) break;
+			let t = bt.Thing;
+			if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain')) || (t.Health <= 0) || (target && t.IsFriend(target)) || !SWWMUtility.SphereIntersect(t,level.Vec3Offset(pos,vel),16) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+			deto++;
+			break;
 		}
+		bt.Destroy();
 	}
 	override void OnDestroy()
 	{
@@ -1058,16 +1070,19 @@ Class BiosparkBeam : SWWMNonInteractiveActor
 		}
 		nextpos = t.Results.HitPos;
 		double closest = double.infinity;
-		foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+		let bt = BlockThingsIterator.Create(self,500);
+		while ( bt.Next() )
 		{
+			let t = bt.Thing;
 			double dist;
-			if ( (!(t is 'BiosparkHitbox') && (!t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)))) || ((dist=Distance3DSquared(t)) > 250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+			if ( !t || (!(t is 'BiosparkHitbox') && (!t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)))) || ((dist=Distance3DSquared(t)) > 250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
 			Vector3 dirto = level.Vec3Diff(nextpos,t.Vec3Offset(0,0,t.height/2));
 			if ( dir dot dirto < .2 ) continue;
 			if ( dist > closest ) continue;
 			closest = dist;
 			tracer = t;
 		}
+		bt.Destroy();
 		if ( tracer )
 		{
 			Vector3 dirto = level.Vec3Diff(nextpos,tracer.Vec3Offset(0,0,tracer.height/2));
@@ -1363,16 +1378,19 @@ Class BiosparkArc : SWWMNonInteractiveActor
 		else
 		{
 			double closest = double.infinity;
-			foreach ( s:level.Sectors ) for ( Actor t=s.thinglist; t; t=t.snext )
+			let bt = BlockThingsIterator.Create(self,1500);
+			while ( bt.Next() )
 			{
+				let t = bt.Thing;
 				double dist;
-				if ( !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 2250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
+				if ( !t || !t.bSHOOTABLE || (!t.bISMONSTER && !(t is 'BossBrain') && !t.player) || (t.Health <= 0) || (target && t.IsFriend(target)) || ((dist=Distance3DSquared(t)) > 2250000) || !CheckSight(t,SF_IGNOREVISIBILITY|SF_IGNOREWATERBOUNDARY) ) continue;
 				Vector3 dirto = level.Vec3Diff(nextpos,t.Vec3Offset(0,0,t.height/2));
 				if ( dir dot dirto < .2 ) continue;
 				if ( dist > closest ) continue;
 				closest = dist;
 				tracer = t;
 			}
+			bt.Destroy();
 			if ( tracer )
 			{
 				Vector3 dirto = level.Vec3Diff(nextpos,tracer.Vec3Offset(0,0,tracer.height/2));
diff --git a/zscript/weapons/swwm_splode_fx.zsc b/zscript/weapons/swwm_splode_fx.zsc
index 5a7dd5f52..7676aad66 100644
--- a/zscript/weapons/swwm_splode_fx.zsc
+++ b/zscript/weapons/swwm_splode_fx.zsc
@@ -245,21 +245,18 @@ Class ExplodiumMagHitbox : Actor
 			return;
 		}
 		SetOrigin(target.Vec3Offset(0,0,-height*.5),false);
-		bool breakout = false;
-		foreach ( s:level.Sectors )
+		let bt = BlockThingsIterator.Create(self,256);
+		while ( bt.Next() )
 		{
-			for ( Actor t=s.thinglist; t; t=t.snext )
-			{
-				if ( (t == self) || !t.bSHOOTABLE || (t == target.target) || t.IsFriend(target.target) || !SWWMUtility.BoxIntersect(self,t) )
-					continue;
-				target.bKILLED = true;
-				target.SetStateLabel("Detonate");
-				Destroy();
-				breakout = true;
-				break;
-			}
-			if ( breakout ) break;
+			let t = bt.Thing;
+			if ( !t || (t == self) || !t.bSHOOTABLE || (t == target.target) || t.IsFriend(target.target) || !SWWMUtility.BoxIntersect(self,t) )
+				continue;
+			target.bKILLED = true;
+			target.SetStateLabel("Detonate");
+			Destroy();
+			break;
 		}
+		bt.Destroy();
 	}
 	override int DamageMobj( Actor inflictor, Actor source, int damage, Name mod, int flags, double angle )
 	{