Framerate is fine, but if I suddenly look in a different direction, usually 90 degrees or so left or right, the FPS drops to 1 for at least a seond, and then recovers. It's repeatable and annoying especially during a wave when its total chaos.

I suspect it is because you are decaching texctures or something alogn those lines, and I know the game is no longer supported but it woudlbe nice fi there was a fix for this and the invisible dinos (view distance) bug.