"LLVMpipe is an especially interesting Gallium3D driver since it
allows accelerating the state trackers atop any modern CPU, but for
any close to decent level of performance when using OpenGL you need
a hefty multi-core CPU (here's some LLVMpipe benchmarks just from
last week) that supports the latest SSE4 instructions as well.
While some OpenGL games will run with LLVMpipe and the performance
of this driver that leverages the Low-Level Virtual Machine is much
faster and better than Mesa's old software rasterizer or the
Gallium3D Softpipe driver, Compiz nor the GNOME Shell (and most
other compositing window managers) yet work with this driver.
"LLVMpipe fails with the GNOME Shell and Compiz..."