Object culling and off camera performance

Can anyone explain what happens to particles and objects that are out of the camera frame? Do they continue to run and take up performance or do they not exist or do they wait for the camera?

Thanks

It depends to what culling mode of particle system is set.

https://docs.unity3d.com/Manual/PartSysMainModule.html → Culling Mode

Dude you just save me so much processing time. I had tonnes of hidden particles that needed to be turned off. Best bit of advice I’ve got in a long time. No idea it existed.