oprofile was inconclusive. 30-45% of time spent in an "anon" function.
Looking closer at the timing graphs, it looks like for whatever reason it takes twice as long every here and there. Something getting dropped on the SteamVR end? I wish we still had always-on reprojection; it could rule out timing problems interacting with SteamVR.
WINEDEBUG=-allx1 2019-05
Compatibility Report
System Information
I confirm:
Log is too large to attach (130MB). Most of it is trace:seh stuff.
Symptoms
Near-constant, severe stuttering. Not enough to trigger the fallback room, but you definitely get nauseous in short order.
WINEDEBUG=-all did not seem to apply unless manually run via /tmp/proton_user/run. Even then, it didn't impact performance at all.
Reproduction
Launch the game. If you perform the start-up calibration and enter the main lobby it's much more pronounced.