Fetid Pool ground effect is a frame killer

I've been in there twice now and both times I drop to 15 FPS when those swirls are around me. This last time I found a wall with no swirls around it and went back to 30 FPS when I stood there. Everywhere else I was at 15 FPS or less. Please fix this. Also, if this effect made its way into any maps, please fix it even faster.