While the Ubuntu 13.10 desktop isn't using Mir/XMir by default, the packages are available within the archive for those wanting to test out the next-generation display server for Ubuntu. To see how the 2D/3D performance is when running under XMir with the Unity System Compositor, I ran some new benchmarks using this week's Ubuntu 13.10 release.
From an Ubuntu 13.10 installation, switching over to an XMir-based Unity 7 desktop environment is as easy as running sudo apt-get install mir-demos unity-system-compositor. Assuming you're using the open-source graphics drivers that support Mir, you should be in good shape and after a restart will be within the new environment.
Months ago the Mir/XMir performance was very bad but the performance has been in reasonable shape since August when composite bypass support was added. This article is just looking at the Ubuntu 13.10 stock performance with an X.Org Server versus running the same Unity 7 desktop under XMir/Mir with the unity-system-compositor using the Saucy packages as of 18 October. For those interested in Mir benchmarks from other environments, see my multi-desktop Mir benchmarks from September.