If you have used Spam Karma in the past but are not using it any longer Weblog Tools Collection has some tips for increasing WordPress performance after deleting Spam Karma.
I used Spam Karma since it first came out and was really pleased with the results but after reading Tom Raftery’s article on preventing comment spam using WP 1.5, htaccess and Referrer Karma, I dropped Spam Karma. I’m happy to say that I have gone almost a week with no comment or trackback spam. Admittedly, this technique is not for those that are uncomfortable with htaccess but all false positives are gone.
We’ll see how it goes.