AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ × 2
GeForce 9600 GT
6 GB RAM DDR2
In Unigine Heaven 3.0 running at Medium settings and fullscreen 1920x1080 XMir was slower than X server by literally 0.3 FPS and it had 9 points less. There is also that thing with GtkPerf being much faster on XMir than on X server with this PC. On XMir I get total time for all tests in the range of 8.30 to 9.10 seconds while on X this times go from 9.60 to 10.90 seconds.
I didn't see tearing in Unity when running on X server. XMir unfortunately has tearing on Nouveau drivers.
Nouevau doesn't have the precise vBlank in NV50 up to NVC0 and newer. Maarten Lankhorst from Canonical made a patch for that but it turned out that while it resolved problems on XMir it also halved the FPS on X server.
I have tearing with nvidia drivers on Ubuntu (GTX 460) but not much possiby because there is compiz there.
In the other hand in my legacy pc (ATi 2600 PRO) I run Xubuntu (which doesn't have compiz) and tearing is everywhere and I mean it!
Mir should fix those kind of problems. Thats why I am asking.
I have enabled "EXAVSync" and it does work fine.
I hope XMir is not pushed into Ubuntu 14.04 LTS. It should be added on 14.10.
Just let the option to use it in Ubuntu 14.04, but not the default.