Would be interesting to have tested using a hosts file (like from http://someonewhocares.org/hosts/ ) instead of an ad blocker. Seems to work very well for me, and it doesn't cause the browser to use loads of RAM.
I'm not sure: isn't it faster to just refuse the request than directing it to localhost and waiting for a time out?
localhost will RST the connection just fine, provided you don't have a webserver listening there.
That's the point. We'd like to see which is faster.
As long as you don't have a firewall blocking traffic to/from localhost, the TCP connection will be reset almost immediately (assuming you don't have an httpd running on port 80) so you won't have to wait for a timeout.