Here are some tips on how to improve the performance of your WordPress blog:
1. Reduce the number of posts on the front page of your blog
2. Install anti-spam plugins in order to prevent spam-bot from creating load on the server.
3. Optimize your WordPress database. You can do through the PhpMyAdmin tool in your cPanel.
4. Install a caching plugin such as WP-Cache or WP Super Cache.
5. Decrease the number of external and internal links on your pages. Leave only the most important ones.