Unity 2019.4.20f1 to 2020.2.6f1 First, Unity is awesome! I will stick to LTS versions for me but I tried upgrading. I had some minor issues to resolve regarding packages I am using but otherwise things seemed fine. While working for a bit, I noticed the editor was stuttering. I noticed some odd things, not saying they are indicators, like the stats window was displaying high values… so I checked the memory in Windows task manager too. Project normally uses ~1.5GB RAM and things are quick, 2020 was at 6.5GB and while watching it for just a couple minutes out of the editor and it climbed up to 8.5GB. (FYI 32GB RAM ~40% usage at the time) I also made a build. I had errors saying it couldn’t find the project file FileStreamIO… when it does it’s reload at build and errors about GUIUtility process event. All hitting the second the game view blips out when building. Build & Run would fail. But build only would complete with the same errors and the game would play as normal. I’m not looking for resolution for my case. I just wanted to leave the feedback here as a direction for possible investigation. I can send log if requested.
Unity devs don’t generally take any development action based on forum threads. If you want Unity to take a look at these issues, here’s the bug reporting process.