Hi, I got this working. You can't use wine with your own prefix afaik since it doesn't authorize with steam properly, so you have to go through steam. All you need to do is add the .bat to your steam library and tell it to run under proton. When you launch the game you might get a frozen image of the loading icon, just open the console and do "map c1a0" and it should load correctly.

Also fyi, you might have to manually update BXT with the new version since the included updater tool did not work (at least for me)

1. Create Game
2. Select bunnyrace
3. start Ezezezez

I got the same issue and i found out that after the update something happened and my computer was using 99% of my ram when only a chrome was open, I fixed this issue by going to regedit and went to this location

After that i dubble click on start and change the value from 2 to 4 then i restarted my computer, after that i never got fps drops again