I was hit by this for quite a while in KDE 4.3.3, and 4.3.4 didn't fix it:
It's a common bug but many people don't notice unless they monitor their CPU usage or temperature. The two following patches fix the problem:
but they didn't make it in time for 4.3.4. I applied them locally and they seem to fix this bug.
*** Bug 264092 has been marked as a duplicate of this bug. ***
Created attachment 216023 [details, diff]
One file patch made from comment 1 links.
One file patch I made from links added by reporter. I can confirm that those changes fix this bug.
4.3.5 is in portage now, is it worth backporting?
Not worth, 4.3.5 is our stable target.
Thanks for the patch anyway