What is pre/base pass in the GPU profiler? Any tips on reducing those things?

Hey all! Been working on optimizing my project as much as possible it runs really well, rn I’m pushing a constant 100 frames but really been trying to hit 144.

I notice in the GPU profiler pre pass and base pass both take quite large chunks of ms. There doesn’t seem to be any real documentation on what these even are (much less profiling them properly) and other similar threads to this one have no real answers.

So, my question is this; what is pre/bass pass? Any good ways to reduce it or make it run better?

Any help appreciated thanks.