It’s been quite a while since I started to work with some statistics about what my plugin does, observing the kind of spam being blocked and it’s been quite cool to see:

Most of the spammers are posting way too fast and they’re killed by my speed limit checks. The link counter catches a few, but that’s not too many coming through. Finally as a last catch, the blacklist – also not that much work here…

But what’s the reason? Captchas and other additional work to verify human beings are not a big blocker as they are just a little more effort. They don’t really impact on the number of spam posts per minute. But if you actually have to wait for the post the way my plugin wants you to, the numbers go down drastically and spamming gets less effective – until they realize what multithreading is about.