diff --git a/src/actor.h b/src/actor.h
index 043f07ae5..be3f28ec6 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -401,6 +401,7 @@ enum ActorFlag7
 enum ActorFlag8
 {
 	MF8_FRIGHTENING		= 0x00000001,	// for those moments when halloween just won't do
+	MF8_INSCROLLSEC		= 0x00000002,	// actor is partially inside a scrolling sector
 };
 
 // --- mobj.renderflags ---
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 2e16347db..1fb7e259d 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4098,6 +4098,7 @@ void AActor::Tick ()
 			CheckPortalTransition(false);
 			LinkToWorld(&ctx);
 		}
+		flags8 &= MF8_INSCROLLSEC;
 	}
 	else
 	{
@@ -4250,12 +4251,16 @@ void AActor::Tick ()
 
 		// [RH] Consider carrying sectors here
 		DVector2 cumm(0, 0);
-		if ((level.Scrolls.Size() != 0 || player != NULL) && !(flags & MF_NOCLIP) && !(flags & MF_NOSECTOR))
+
+		if ((((flags8 & MF8_INSCROLLSEC) && level.Scrolls.Size() > 0) || player != NULL) && !(flags & MF_NOCLIP) && !(flags & MF_NOSECTOR))
 		{
 			double height, waterheight;	// killough 4/4/98: add waterheight
 			const msecnode_t *node;
 			int countx, county;
 
+			// Clear the flag for the next frame.
+			flags8 &= MF8_INSCROLLSEC;
+
 			// killough 3/7/98: Carry things on floor
 			// killough 3/20/98: use new sector list which reflects true members
 			// killough 3/27/98: fix carrier bug
@@ -5079,6 +5084,8 @@ AActor *AActor::StaticSpawn (PClassActor *type, const DVector3 &pos, replace_t a
 	{
 		level.total_secrets++;
 	}
+	// force scroller check in the first tic.
+	actor->flags8 |= MF8_INSCROLLSEC;
 	return actor;
 }
 
diff --git a/src/p_scroll.cpp b/src/p_scroll.cpp
index f2661a2a1..d8666d9a7 100644
--- a/src/p_scroll.cpp
+++ b/src/p_scroll.cpp
@@ -256,6 +256,11 @@ void DScroller::Tick ()
 		case EScroll::sc_carry:
 			level.Scrolls[m_Affectee].X += dx;
 			level.Scrolls[m_Affectee].Y += dy;
+			// mark all potentially affected things here so that the very expensive calculation loop in AActor::Tick does not need to run for actors which do not touch a scrolling sector.
+			for (auto n = level.sectors[m_Affectee].touching_thinglist; n; n = n->m_snext)
+			{
+				n->m_thing->flags8 |= MF8_INSCROLLSEC;
+			}
 			break;
 
 		case EScroll::sc_carry_ceiling:       // to be added later