It could be anything. Maybe some orphaned process was running in the background and leaking ram, or something. It's futile to speculate now about that.
Also, the -recently added- "pgo" USE flag could have something to do with that. Not sure, since I didn't bother to investigate it's true purpose on firefox. I really don't think that the kernel has changed in a significant way in this regard since the latests 2.6.x releases. But I certainly didn't read *all* the kernel changelogs. -- Jesús Guerrero Botella
