Since auto-upgrading to 54.0b9 version (using Win 7), the Firefox browser hangs for 1-2 second (not responding) in every 5-7 seconds. When it hangs (during that 1-2 seconds), when I typed some text on the form, the characters didn't appear until after that 1-2 seconds lag time. When I scroll down a webpage, it stopped for that 1-2 second and them scrolled again. During that lag time, even the mouse cursor didn't change to an arrow if I point the cursor to an active link. I noticed that the Hard disk light was on during that lag time which may be that Firefox was trying to use the SSD/HDD. I have tried re-installing, refresh firefox, boot in safe mode, with no plug-ins, switching of the Trendmirco internet security, delete places.sqlite to places.sqlite.old and places.sqlite-journal to places.sqlite-journal.old (if it exists), deleting session js files, switching off hardware acceration. All failed. Please help. Thanks.