If you have root access and you are willing to apply a hack system-wide (so it will affect other users on the same machine too), a quick hack that will do what you want would be to list the offending site in
(If you are not using Linux then replace
127.0.0.something-else doesn't necessarily work with other operating systems)
This will trick the system to think that the offending name maps to a local IP address. Your web browser will hit up the local web server running on the same machine, which may or may not exist but one way or the other it will be fast instead of timing out.