I have noticed, for the longest time, a problem while downloading large files in Firefox (version 3.6.10, but it happened with earlier 3.*.* versions). I'm using Norton Internet Security 2011, but even with version 2010 I had this problem.
In task manager, I can see Firefox's memory usage climb up and up, but never dip down, even when few tabs are open and I'm not using it. Someone suggested an Addon could be causing a problem. Sure enough, when I disable Norton IPS (Intrusion Prevention System) restart Firefox, and go to download the file again, the memory usage remains more or less constant. I've tried this many times to make sure this is the source of the leak, and it is.
My guess is that IPS is trying to analyze the download, but somehow it ends up loading the entire download (2.8 GB in this case) into memory. Can anyone suggest a fix, other than just disabling IPS while downloading large files? I don't want to disable it out right, because it has saved me several times.
Additonally, the download appears to move about 3X faster with IPS disabled. For example, I remember yesterday it was moving at about 300 KB/sec whereas right now (with IPS disabled) it is moving at about 900 KB/sec.
Thank you for your help,