update: I have also found that prefetching is active in the Epiphany browser as well. The instructions to de-activate it are the same, see below.
I recently found out that Firefox has a feature called “prefetching” that tries to pre-download items that it suspects you might click on soon. This could help in pre-downloading content that you would visit next (ie; it is linked on the page you are visiting therefore you might access it next), but it can also have the nasty negative effect of wasting your bandwidth on items you don’t ever want. This can also download cookies from sites you haven’t visited, etc. Seems like a nasty feature to me!
I also found that this prefetching feature will cause your connection to the ubuntuforums.org (and a few other sites) to be refused if you are also going through a squid proxy. So, this is a quick suggestion on how you can disable prefetching in Firefox.
Disable Prefetching in Firefox
In your browsers address window enter the address:
This will pull up your browser settings (in FF3 it will warn you that there be dragons ahead! Just accept the warning.) You’ll now want to search for the following string, which you’ll toggle off:
To toggle off this setting simple double-click the listing and it will set to false. Prefetching items that you might download is now disabled. Your machine will now kindly only download the content, cookies and images that you actually access directly.