When I use CAEmitterLayer on my screen, it does not affect performance no matter how many layers and particles I use. I always see CPU usage zero.
Is it possible to know how CAEmitterLayer affects performance or even measure this?
How to measure CAEmitterLayer performance impact?
Emitters primarily use GPU resources, so you might check your vertex & fragment fill rates. But they are also extremely cheap, so it may simply be the case that your usage of them isn't possible to measure.