Black Mesa
I found out that the native linux version has very poor performance compared to running it with proton, not to mention having missing graphics features. In order to force steam to run it with proton go to properties > compatibility, and check "force the use of a specific steam play compatibility tool." In addition, enter -oldgameui in the launch options. I ran it with the latest proton by Glorious Eggroll and had a stable 60 FPS where it was dropping to 15 natively.
I'm still kind of baffled that the proton version runs so much better. If it runs that poorly, than why even say it supports linux at all?