Comment Spammers Are Evil Bastards
OK, let me rephrase that: Comment spammers are evil, but the folks who let their systems be infected by malware that turns their systems into zombies are just as bad.
On a nightly basis, the server running this site is set to do usual middle-of-the-night maintenance chores: update cPanel and various other software packages I have installed (including the great ConfigServer products), check the logs, run AWStats, etc... . Obviously, it pushes a bit of load, but I tried to spread it around the night a bit so Apache is still responsive to the few requests that will come in. Last night, this server was attacked hard by comment spammers, with my comment script on this site getting hit by zombied computers at a rate of about 100 per second. My various MT Plugins were fighting off a lot of it, but the load was still up to 30 in top at many points through the evening (according to my log reports I read in the morning). Web pages were still getting served, but just not as quick as they could've been.
Renaming my comment script, and installing this plugin hasn't put my load above .5 all day. There are still tons of requests coming in for my old comment script, but they're just getting 404s or sand trap redirects, which Apache can serve up without issues or load.