Originally Posted by keyser7777
Following the last comment, I've disabled kwin desktop effects (kde 4.2.1 compiz equivalent) and the film in cause it's being rendered smoothly, with very low cpu usage. However, with desktop effects turned on, there is a very high cpu usage and the rendering is very slow.
Is this a known issue?
A number of people have reported this, and it's turned out to be the compositing manager using indirect instead of direct rendering, which has quite some overhead. I'm not sure how to configure this for kwin.