Spamhaus is either down, or blocking my DNS queries right now. This delays my SpamAssassin checks as each one waits 10 seconds to timeout. To disable the Spamhaus checks put the following in your ~/.spamassassin/user_prefs

score RCVD_IN_ZEN 0
score RCVD_IN_XBL 0
score RCVD_IN_PBL 0