Mozilla’s latest update 3.0.11 is too slow in tab switching (though mozilla claims 3.0.11 to be the fastest mozilla)and the degree of slowness goes to such an extent that users are now getting frustrated . I also experienced the slowness and switched to some other browsers just to come back to mozilla firefox and try and solve the problem.
I tried all the method given online, deleting the cookies and clearing the temp folder ,creating another profile,opening mozilla in safe mode, removing the favourite bookmarks and removing all the plugins . But the problem of slow tab switching persisted , I was left with no other option than to roll back to Mozilla Firefox previous version. I read on few blogs that 3.08 has a similar problem so i switched to 3.0.5 and now everything works absolutely fine.I have installed all my plugins and the memory usage has decreased substantially.To my understands firefox 3.0.11 has some security fixes and have tried to make mozilla faster, because of which it starts consuming a lot of memory and then it affects other system processes as well.
Though I hope firefox to fix this issue in the next version it releases , you can refer to mozilla forums if you are experiencing similar problems:
My experience with other browser’s taught me that Firefox can never be replaced.It is the best browser available currently.