Comment 291 for bug 113201

It is indeed horrible!

Today I've tried accessing blender.org whose name servers do not respond.
When using PAC whole browser locks up for ~15s, unfreezes then locks up again.

Switching proxy to manual or direct resolves issue, though browser seems to freeze for almost second every 10-15 seconds while another tab tries to load page for ~1min.

This is on Win7 with FF4.0

I guess this can be reproduced by setting up a dns zone with ns records pointing to dead servers (or finding such domain on internet).