Once again, I find myself turning to this wonderful series of tubes for help on a weird problem.

I have Firefox (Iceweasel) on all the computers I regularly use. One of these computers has had a persistent problem.

After using it for awhile, it takes a really long time to look up hostnames in DNS. And after upgrading to Firefox 3, it got much worse. Not only did name resolution get slow, but sometimes page loads would get exceptionally slow as well. I could have 5 tabs open, and all of a sudden at the magic moment, nothing would load on any tab. It was as if I was being hit by 75% packet loss. And new pages wouldn’t load, either.

tcpdump showed Firefox not even sending out packets at these times. After a few minutes, it might be back to normal. But I could always quit and restart and it would be fine.

Now, here’s the weird thing: I’ve eliminated every possible difference I can think of between this one machine and the others I use Firefox on. My plugins and extensions are the same set with the same versions. My configuration is the same. When this problem is happening, other network-related programs (even other web browsers) on the same machine are working fine. Nobody else here seems to be having this problem.

Any ideas?