When using Chrome/Chromium when hovering over certain elements (also hyperlinks) the cursor gets slowed down substantially.
This stops when I turn off desktop effects.

My configuration: Ubuntu 12.04 with KDE 4.8.5. Graphics card ATI Radeon HD 5750 (up-to-date proprietary driver)

Does this happen universally across all websites, or just on certain sites?

See his other post viewtopic.php?f=67&t=119293 - seems some general driver installation issue.
We had *tons* of that because Ubuntu screwed fglrx/nvidia ./. radeon/nouveau and users ended up on the software rasterizer...

Since this post I have reinstalled the original Ubuntu with KDE desktop to just Kubuntu out of box. Its working better (also I kep the original driver) But still I notice the slowing problem sometimes (not that accute as it used to be). It usually dissapears after turning off and back on the desktop effects.

It does not happen when browsing specific pages (but it could be said that feature /javascript rich pages tend to perform worse but just because there is this problem more visible).

I moved to another distribution and now everything runs smoothly.