Works for me with PROTON_NO_ESYNC=1
Yes, of course! I totally forgot to try the game with PROTON_NO_ESYNC=1! Additionally, I also had to set PROTON_NO_FSYNC=1, because I'm using a custom kernel with FSYNC support.
Other than that, it runs pretty amazing. I get a constant 120 fps with no stuttering whatsoever, with the graphics maxed out. Here are the benchmark results:

Works beautifully with my DS4 gamepad too! But that's thanks to Steam, I think.
The only thing it doesn't work is online multiplayer, but that's expected since this game has GFWL integration and that's a defunct service.
It uses PulseEvent(); that's unfixable with esync.
So the game now works out of the box, I see.
So the game now works out of the box, I see.
Yup, it does. Proton now automatically disables esync/fsync for this title. I wonder if these game-specific workarounds are private because I couldn't find them in this repo...
The runtime config options are being applied by Steam's whitelist config, even though this particular game is not currently whitelisted.
So this list of workarounds is indeed private? Because I'll be opening a new issue for a different game that also uses PulseEvent() and it'd be awesome if Steam automatically disabled esync/fsync for that one too.
PROTON_NO_ESYNC=1`!x1 2020-07PROTON_NO_FSYNC=1`,x1 2020-07PROTON_NO_ESYNC=1`x1 2020-07
Compatibility Report
System Information
I confirm:
steam-21660.log
Symptoms
Once you click to "Launch STREET FIGHTER IV" in the game's launcher, an empty black window opens and the game seems to freeze.
Reproduction
Just try launching the game.