I’ve been recently trying to run the deep profiler to understand why things are taking so long. It’s about 14 seconds for me, 30GB of assets, scenes that have about 100-200 GameObjects (not created by assets).
I’ve found two culprits so far (well I don’t know if the asset itself is to blame), but people can follow the progress here for:
Rewired: Rewired - Advanced Input for Unity page-104#post-4426885
Odin Inspector: [RELEASED] Odin Inspector & Serializer - The Ultimate Workflow Tool ★★★★★ page-16#post-4426891
I’ll post a summary back here when both of those threads conclude.
I’ve been struggling with this a lot. I’ve promised to never use Unity again when I finish this project, its been 4 years of time at night spending maybe 30-35 seconds on average to test a simple code change. I don’t know how much time I’ve spent over those years waiting for Unity to just recompile+enter play mode. I appreciate the work that Unity has done to make it possible for me to make a hobby dream come true, I just wish they used their own engine to try and release an actual big-ish game. Not a cinematic, not some ECS toy project, not a mobile Flappy Bird clone, but an actual game (use Xbox One S as a target).
Unity could benefit from that experience of using its own tools, then we all would 
Other engines got massive steps forward when their developers were forced to use them for more than toys.