The first thing to do while checking out an overloaded blog is to see if it's being spammed. It is one of the top reasons why blogs go crazy on CPU usage. Check the "Comments" link on your WordPress install. If you're seeing the same sort of comments as the mail you see in your mail account's Inbox from spammers, you'll need to install a plugin to help deal with the incoming flow of spam.
There are a lot of anti-spam plugins that are available for WordPress, but listed below are only ones that work the best on DreamHost servers:
- Pros: Spam checking happens off server, low impact on server overhead, works with most feedback forms.
- Cons: Needs an API Key in order to run.
- Pros: Easy to install via WordPress, blocks users who don't have 'cookies' (which should only be bots), works with Akismet
- Cons: Requires editing your .htaccess
- Using a combination of plugins is recommended, but keep in mind that the CAPTCHAs plugin is not always user friendly.