I have concerns still:

* There is no evidence of a Mutter bug yet that is affecting any other
program.

* There is evidence of heavy rendering in mrv2 causing those 20ms
periods spent in eglSwapBuffers. There's really nothing else that can
cause it other than an actual high GPU workload or the workload being
relatively too high on a system that is in a low power mode. This can
happen on very short time intervals if for example your render loop
blocks and puts the CPU and GPU to sleep on a regular basis. They will
stay in a low power mode even though you sometimes need them higher to
maintain a smoother frame rate and faster render times. So make sure
there are never any blocking calls (or the equivalent of a sleep) in the
render loop.

* Swap interval zero AND fullscreen direct scanout both require the
toolkit to provide three buffers at a minimum to ensure the client is
never blocked in acquiring or submitting new buffers while the
compositor holds another one. If you use swap interval zero and your
fullscreen window gets direct scanout at the same time then there's a
chance the toolkit will need four buffers to prevent delays in that
situation. I don't think this is well known to OpenGL developers, it's
just something I learned from working on compositors.

Please try enabling this toggle:

  Alt+F2 > "lg" > Flags > DISABLE_DIRECT_SCANOUT

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Desktop Bugs, which is subscribed to mutter in Ubuntu.
https://bugs.launchpad.net/bugs/2153492

Title:
  Regression in OpenGL Wayland performance (not NVidia issue)

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