Going through your blog, I can see why your host has sent you this email.
You have 20 posts showing on the front page of your blog, which means the databases has to be queried to retrieve 20 posts, their related posts and tons of other sidebar links, each time the front page of your blog is opened!
Now this wouldn’t be a big deal if you are using something like wp-supercache or other cache plugins to cache the data so that the database doesn’t have to be queried each time, but I guess you aren’t doing that.
Here are the steps you can take:
- Reduce the number posts on front page to 5 or less.
- Use cache plugin like wp-supercache.
- Open your database in phpmyadmin and optimize it (check all tables and then choose optimize option at the bottom of the page (it could be under a drop down menu), you can also request your host to do the same.