LG sets the XAtom
NETWM_BYPASS_COMPOSITOR which disables desktop composition. Without this the render pipeline is buffered and guest mouse cursor updaes lag behind a frame or two. This is because LG has to composit the mouse cursor instead of relying on hardware cursor support. So in short, not a bug, a feature
If you really want to disable this, comment out or remove lines 1202 to 1217 in main.c in the client, however you likely will find the application performance suffers.
1202 Atom NETWM_BYPASS_COMPOSITOR = XInternAtom(
1207 unsigned long value = 1;
1215 (unsigned char *)&value,