Comment 3 for bug 129142

Possibly, but may be the same underlying cause, just that today's update exacerbated the problem.

I'm now seeing 100% CPU even in the preview Window - I was previously using Matrixview full screen (1680 x 1050) without any problems, but now the framerate has dropped right off and the screensaver stutters quite badly and as I'm only single-core it can take several seconds to get back to desktop once the screensaver kicks in.

Was digging around to see if Update-manager logs to a file somewhere, that might give a hint as to what update borked performance today.