The CPU load depends on the time a web server spends executing a script whenever a visitor opens a webpage on a particular script-driven website. Static HTML websites use barely any CPU time, but this isn't the case with the much more sophisticated and functional scripts, which use a database and display dynamic content. The more clients open such a site, the more load will be produced on the hosting server and if the database is very large, the MySQL server will be loaded also. An illustration of what could cause high load is an online store with thousands of products. If it's popular, many people shall be exploring it all at once and if they seek out items, the entire database which contains all of the products shall also be continuously accessed by the script, resulting in high load. In this light, having CPU and MySQL load statistics will give you an idea of how the site is doing, if it has to be optimized or if you simply need a more efficient hosting solution - if the Internet site is really popular and the current setup cannot cope with the load.