Welcome to WebmasterWorld Guest from 18.104.22.168
I'm already blocking by IP's but my list was getting rather large.
[edited by: cyberdyne at 1:50 pm (utc) on Jul 12, 2011]
I blocked all .ru visitors with 'deny from .ru' (since the only .ru visitors to my sites are spammers).
connection/lookup is slow or if it fails, then the user's request will also be slow or fail