As the latest Intel Ivy Bridge Linux graphics benchmarks to publish, here is a comparison of some of the different desktop environment options of Ubuntu 12.04 LTS when using the Intel Linux graphics driver on the Core i7 3770K with its HD 4000 graphics. The desktop environments being compared include Unity, Unity 2D, KDE, and Xfce. The default Ubuntu Unity desktop with Compiz continues to have problems for the open-source friendly company's drivers.
This testing is similar to previous comparisons looking at the impact of graphics performance under different drivers/hardware and tossing the popular desktop environment options into the mix. The difference this time around is using the latest open-source Intel Linux graphics code (Mesa 8.1-devel + Linux 3.4) while using the latest-generation Ivy Bridge hardware.
Ubuntu 12.04 LTS and all of its desktop environments were left in their stock configurations. When testing KDE SC 4.8.2, the desktop was tested with its default settings and then again when the desktop effects were suspended upon running full-screen OpenGL applications.
All benchmarking was handled via the Phoronix Test Suite.
Some recommended related reading would be Tweaking KDE's KWin For Linux Gaming Performance, Ubuntu 12.04 Desktops Impact Performance, Power Consumption, and Gaming/Graphics Performance On Unity, GNOME, KDE, Xfce.