https://bugs.freedesktop.org/show_bug.cgi?id=34418
--- Comment #5 from Marek Olšák maraeo@gmail.com 2011-02-19 07:56:55 PST --- noimmd disables the "immediate mode" style of rendering, which means vertices are written directly to the command stream for the GPU instead of being stored in vertex buffers. There is something fishy here because I can't reproduce it for whatever reason, so there is something wrong either with my machine or yours.
Bug 34336 is likely a duplicate of this one.