One of my WP sites is using a lot of CPU, and I am wondering if this is caused because of the high number of spam comments it is getting. Can that be the case? Is there an easy way of checking that?
Any time your traffic goes up your CPU usage will go up. Based on what you're saying it could be bot activity. I'm also assuming you're on a shared host that is overloading the server with 10 billion accounts.
My suggestions include:
- Running a virus scan for WordPress via any number of available plugins
- Minimize the number of plugins you're running, as they can impact your CPU usage
- Decrease your database size, be sure deleted tables are actually deleted
- Add a cache plugin http://wordpress.org/extend/plugins/wp-super-cache/
- Look for unusual/frequent bot activity and block those suckers