[Bug 50599] Regressions with upgrade from kernel 2.6.15-23 to 2.6.15-25

[oSoMoN]

Public bug reported:

Binary package hint: linux-image-2.6.15-25-686

After upgrading to kernel 2.6.15-25 on my laptop (Acer Extensa 4102WLMI, ATI mobility Radeon X700), all the graphical effects in gnome are very slow and the playback of videos (any file type and DVDs) is very slow as well.
Seems to be the same type of issue as reported here: http://www.ubuntuforums.org/showpost.php?p=1158244&postcount=82 (DVD and video playback is choppy / jerky and when you start an app from the panel, there's this short little animation of an extending frame, this animation needs almost 2 seconds to finish and is jerky as well).
Browsing the forums seems to show that the new kernel has a lot of various issues, while falling back to 2.6.15-23 works perfectly fine.

** Affects: linux-source-2.6.15 (Ubuntu)
     Importance: Untriaged
         Status: Unconfirmed

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Regressions with upgrade from kernel 2.6.15-23 to 2.6.15-25
https://launchpad.net/bugs/50599