I finally got the bottle neck, it is facebook. Each facebook showed a message, my firefox sudenly allocating 400 MB and make the whole system jammed. I tried to opened up 7 youtube video and run all of it at onece, nothing happen, but when I open a tab of facebook, it jammed.
Hi Onan,
Not sure but try to turn-off all the unnecesary add-ons \ plugins consuming a lot of system resources.
You could try: http://www.browsermemory.com/
Hope this helps.