Your games on Linux might unknowingly run slower than they need to. My games had inconsistent FPS between different sessions—smooth 144 FPS between stuttering ± 120 FPS—and I couldn't figure out why because all the logs indicated it was running on my dedicated GPU.

First I assumed it was a caching problem due to running distributed computing projects 24/7 [finding primes, not crypto"currencies", don't worry], but it turns out it was in fact arbitrarily using the desktop CPU's integrated graphics instead of the GPU.

Via the Steam game launch options command below one can force the use of one's dedicated GPU—0 or 1 depending on one's PC.

__NV_PRIME_RENDER_OFFLOAD=0 __GLX_VENDOR_LIBRARY_NAME=nvidia %command%