Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:2.0b10pre) Gecko/20110124 Firefox/4.0b10pre The page seems to be this https://services.addons.mozilla.org/en-US/firefox/discovery/pane/4.0b10pre/Darwin Based on Shark profile 26.9% is taken by painting background (including 17.5% PaintGradient) 17.5% is taken by painting borders. 10.4% is taken by nsTextFrame::PaintOneShadow and things under it 7.8% is taken by nsDisplayBoxShadowInner::Draw and things under it (I'll file another bug for the usability issues.)

If I load just https://services.addons.mozilla.org/en-US/firefox/discovery/pane/4.0b10pre/Darwin, scrolling is quite fast. So something in about:addons triggers slow paths.

Bug 623615 is the same issue for the list view, any reason to think this would be something different?

I don't think so. AS given by comment 1 the problem is not in the discovery pane but only happens when content is presented in our pane with rounded corners.

this could be the same as bug 623615. Marking dependency

When you put anything inside a rounded rect with overflow hidden it gets slow.

This should have gotten better.

Lets keep this bug for the Get Add-ons case.

Is this fixed now by bug 716439?

Yes, it is. Can be closed now.

Thanks for the confirmation :) -> FIXED via bug 716439