A few days ago, I my account was suspended. I am on a shared hosting and get about 300 unique visits a day. That is fairly a small amount of traffic to cause a problem on a shared hosting environment.
I have googled “WordPress CPU Usage” and found that the problem is not only isolated to my blog. A lot of people are also complaining on the same issue.
I think this is a problem on the WordPress code. I have read somewhere that at times, it (wordpress) queries the database at least 20 times to display the frontpage! Yikes!
Anyway, for those who are also experiencing this problem, I suggest that you install the following plugins: WP-SuperCache and Bad Behavior. I have gone an extra step by removing the Tag Cloud. I replaced it with direct links (hard-coded) to the tag pages. I also installed Optimize DB – a wordpress plugin that optimizes your database with a single click.