Not sure if it was already mentioned, but if your mesh is not loaded with LoadAnimMEsh (and I assume it isn't, it's rather created at runtime, right?) and if it has mutliple Surfaces, it will be rendered completely, even if only one surface is in the FOV of the camera. But if you have a mesh per surface, fustrum culling will skip rendering of any mesh that isnt in the FOV of the camera.
yeah with this information and Rob suggestions I'm going to go with 1 mesh per surface. Not per emitter in my case for 2 reasons; most of my emitters will be on screen at the same time and I want to keep the surface count low cause that does seem to be the biggest hit.Thanks everybody.