I knew the facts that people were complaining about memory leaks in firefox, but I didn't have any problem partly because I have 4GB machines. But that story has changed after upgrading to firefox 5. '''When I was trying to download 6 100MB files in firefox, memory usage of firefox increased from 200MB to 1.5 GB in 2 minutes'''. Actually it might have been more than that but I killed the process before its memory usage growth became uncontrollable. What is going on? It has never happened before I upgraded to firefox 5. And it happens every time when I am downloading large files.