[Feedback] Proton 4.11 much better than 5.0

From all the games I have on Steam (at least those for windows, anyway), only a handful of them run fine with Proton 5.0. Specifically, those with good performance with 4.11 are Hard Truck Apocalypse, RAGE 1, NFS Rivals, Euro Truck 2 and ATS (yes, I know these two have native linux versions but I was testing stuff, that's why I forced them to use Proton), 18 WOS Extreme Trucker 1 & 2 and many others. Whereas with Proton 5.0 only CarX Drift Racing Online runs fine. Titan Quest AE and GTA 5 have the same problems in both 4.11 and 5.0 - flickering lights and shadows, travelling shadows and static objects (objects that shouldn't travel with the character, such as trash cans and traffic lights), etc. Also, the games that run fine with 4.11 have perfect sound whereas with 5.0 the sound is awful, sometimes it's completely missing. There are just too many games that run poorly with Proton 5.0, so I decided it would be easier to just come here and give you this feedback, instead of spending a whole week reporting bad performance.
Particularly Hard Truck Apocalypse that I mentioned above: with 4.11 it needs 20 seconds tops for the game to load and run and about 10 seconds to create or overwrite a save file. With Proton 5.0 HTA never launches - the mini-window simply hangs on "Preparing to launch HTA..." and that's it. Once I was AFK for over 30 minutes and when I came back HTA was still "prepping to launch".
IDK what you did or you didn't in 5.0 but so far it's the worst Proton version. Seems to me you released it too soon.

Start by comparing Hard Truck Apocalypse under Proton 4.11 and 5.0, focusing on the reported launch hang and save-file timing. The issue covers many games and symptoms, so done would require narrowing this feedback to a reproducible, actionable regression with a defined scope.