Comment 149 for bug 113201

DNS caching is definitely in play, since the blocking that happens is due to us waiting on a DNS response. Purging your DNS cache before step 2 would make the results more useful. Sorry I didn't say so earlier, if you have a chance to test again with that it would be helpful. (Or you can go to a "fresh" host first, since the loading speed of the page isn't going to be affected here, just whether we have the browser locked up while waiting for the DNS response in proxy autoconfig. Comparing vs. Firefox 3 b4 rather than 2.0.0.12 will also probably isolate things better.)