I have two problems with the prewarming of particle systems. Firstly, in one of our scenes it takes quite a long time to see the PS turned on, my guess is that the PS prewarming takes so long. And the second thing is, when the GameObject is deactivated and reactivated, the PS can be seen spreading slowly. So exactly what prewarming is supposed to prevent.
by user 689743366355025931
Hey 
thanks for reporting that, would you be able to simplify your scene and make a bug report?
Just duplicate your scene, remove extra unnecessary parts, validate that the issue still occurs and then navigate to Needle Engine/Report a Bug/Create Bug Report and follow the instructions.
Bug reports helps by providing a clear case of an issue / of issues and significantly can save time of the dev team. Such help is very welcomed 
@marcel Just wanted to follow up here that using the particles sample scene and ticking prewarm on one of the particles causes the scene to load for a very long time on the build, it eventually crashes the tab in a local server due to memory running out
by user 103054507105067008
Could you share the particle system with me?
What’s weird is it has stopped happening now I went back to try again, if I can repro it I will share, sorry for the bump
by user 103054507105067008