This is an interesting article by Paolo Rotolo, it’s a comparison of MIR (in the Xmir version that will be present on Ubuntu 13.10) and the current Xorg.
—
After the announcement of Canonical on Mir, which will be included as a default display server in Ubuntu 13.10, I decided to do some tests (benchmark, in the jargon), to see whether the performances of Mir are comparable to those of the good old X.org (the daemons currently present on Ubuntu), as promised by Mark Shuttleworth on his blog.
All benchmarks were performed with the suite “Phoronix Test” on Ubuntu 13.10 (Saucy Salamander).
I’ve done all the test run on an hardware with low-medium specs (especially the video card), because with a more powerful PC, the differences between X.org and Mir would have been less relevant.