diff --git a/engine/client/r_surf.c b/engine/client/r_surf.c
index 1e0f24482..0e9d0087e 100644
--- a/engine/client/r_surf.c
+++ b/engine/client/r_surf.c
@@ -3035,6 +3035,7 @@ struct webostate_s
 static struct webostate_s *webostates;
 static struct webostate_s *webogenerating;
 static int webogeneratingstate;	//1 if generating, 0 if not, for waiting for sync.
+int webo_blocklightmapupdates;	//0 no webo, &1=using threadedworld, &2=already uploaded.
 static void R_DestroyWorldEBO(struct webostate_s *es)
 {
 	if (!es)
@@ -3063,6 +3064,7 @@ void R_GeneratedWorldEBO(void *ctx, void *data, size_t a_, size_t b_)
 	webostates = webostate;
 	webogenerating = NULL;
 	webogeneratingstate = 0;
+	webo_blocklightmapupdates = 1;
 	mod = webostate->wmodel;
 
 	webostate->lastvalid = cls.framecount;
@@ -3661,6 +3663,7 @@ void Surf_DeInit(void)
 	int i;
 
 #ifdef THREADEDWORLD
+	webo_blocklightmapupdates = 0;
 	while(webogenerating)
 		COM_WorkerPartialSync(webogenerating, &webogeneratingstate, true);
 	while (webostates)
@@ -3870,6 +3873,10 @@ int Surf_NewLightmaps(int count, int width, int height, uploadfmt_t fmt, qboolea
 	unsigned int pixbytes, pixw, pixh, pixd;
 	unsigned int dpixbytes, dpixw, dpixh, dpixd;
 	uploadfmt_t dfmt;
+#ifdef THREADEDWORLD
+	extern int webo_blocklightmapupdates;
+	webo_blocklightmapupdates = 0;
+#endif
 
 	if (!count)
 		return -1;
@@ -3994,6 +4001,11 @@ int Surf_NewExternalLightmaps(int count, char *filepattern, qboolean deluxe)
 	char nname[MAX_QPATH];
 	qboolean odd = (count & 1) && deluxe;
 
+#ifdef THREADEDWORLD
+	extern int webo_blocklightmapupdates;
+	webo_blocklightmapupdates = 0;
+#endif
+
 	if (!count)
 		return -1;
 
diff --git a/engine/gl/gl_backend.c b/engine/gl/gl_backend.c
index 641407a94..a546579eb 100644
--- a/engine/gl/gl_backend.c
+++ b/engine/gl/gl_backend.c
@@ -5511,11 +5511,22 @@ void GLBE_SubmitMeshes (batch_t **worldbatches, int start, int stop)
 	}
 }
 
+#if (defined(GLQUAKE) || defined(VKQUAKE)) && defined(MULTITHREAD)
+#define THREADEDWORLD
+#endif
+
 void GLBE_UpdateLightmaps(void)
 {
 	lightmapinfo_t *lm;
 	int lmidx;
 
+#ifdef THREADEDWORLD
+	extern int webo_blocklightmapupdates;
+	if (webo_blocklightmapupdates == 3)
+		return;	//we've not had a new scene to render yet. don't bother uploading while something's still painting, its going to be redundant.
+	webo_blocklightmapupdates |= 2;	//FIXME: round-robin it? one lightmap per frame?
+#endif
+
 	for (lmidx = 0; lmidx < numlightmaps; lmidx++)
 	{
 		lm = lightmap[lmidx];