You mentioned you “reinstalled Manjaro”… and this is also your first post… so I’m guessing that you perhaps freshly installed Manjaro; maybe replacing Windows? If so, then you might be in my shoes about 4+ months ago… Welcome aboard! 
My GNU/Linux gaming is strictly under Steam/Proton at the moment, and I’ll share some settings/tips specifically for Steam… but before I do that, two questions:
- Do you have an AMD GPU/APU or and nVidia GPU?
- If you have an nvidia GPU, are you using the Proprietary driver or the OpenSource driver?
My understanding is that the opensource driver isn’t robust enough to offer excellent game play on nVidia cards… I’m an AMD GPU user, so there really isn’t much more explanation I can offer in this case.
Here are my Steam tips…
- Read How should I opt into the steam Client Beta? - #4 by Daniel-I and ensure you have both opted into the “Steam Beta” and have enabled “Steam Play”
- Visit https://www.protondb.com/ and lookup your game(s). Sometimes people will post adjustments they had to make to get things working… specific Proton version, launch commands, etc
- Now that you have enabled “Steam Play”, you’ll have the option to select a specific proton version per game in it’s “Steam properties” if you found that’s what worked for others @ protondb.com
- Sometimes (I think CIV 5 is one example) even a game that says it has native Linux Support in Steam will run better if you force it to use “Steam Play”/Proton… usually people report this @ protondb.com if that is the case
Hopefully something I’ve posted here helps you… or teases some extra details out that leads to your solution.
P.S. I think opting into the Steam Beta also gets you access to the latest “Proton Experimental” builds. I’ve seen Proton Experimental get updated up to a few times per week, so I imagine there are lots of tweaks fixes that a non-Beta participant would miss out on. I like to check https://steamdb.info/app/1493710/patchnotes/ for the “Proton Experimental” changes.