I once wrote about the problem when the FPS fell for unknown reasons. I did not get an answer then, and it was not critical. But now, when I with SilentKnight make a big map for a custom event - this has become a big problem. We sometimes have 25 fps on the map. Initially, I thought it was caused by a large number of polygons. I reduced them as much as I could, my LODs and the culling are very large but this does not help. Turning on monitoring, I discovered that when I have 25 FPS, then the