2D Performance Also Impacted By Unity On XMir

[TheOne]

The composite bypass they mean is in the Mir side. It means Mir is trying to realize all of the operations needed for compositing, even when working with a fullscreen app, so this affects everything.
The rendering of the desktop as a fullscreen window (independently of who controls the contents, as long as it's not Mir) implies that Mir doesn't really need to handle any compositing, so you can avoid those operations (that's why it's called a bypass). X still needs to do its inner compositing, as long as your real app is not in fullscreen mode, in which case a well thought window manager bypasses it (GNOME, Unity, KDE, XFCE, and maybe some others include this feature), too.
speed).

mmm, so the fix mentioned by the canonical developer may actually improve XMir performance.

...
The second, what XFCE's devs say has nothing to do with Ubuntu's and flavor's decisions, that's why I asked. I'm aware they don't plan to switch to Mir, so it's either X.org or XMir.
There must be a way to set it up otherwise, though, for the sake of testing.

This instructions seems to be pretty easy to follow (what they are lacking is the xmir part):

http://www.olli-ries.com/running-mir/

[mrugiero]

mmm, so the fix mentioned by the canonical developer may actually improve XMir performance.

Yes, yes it should.
If it works as I think it does (running an actual X server over Mir), and Mir is non-interfering enough (just pointing to the surface when it's a fullscreen app) it should run at around the same speed as a direct X server.

This instructions seems to be pretty easy to follow (what they are lacking is the xmir part):
http://www.olli-ries.com/running-mir/

I'll look into it.