The CPU load depends on the amount of time a web server spends executing a script any time a visitor opens a webpage on a certain script-driven website. Static HTML sites use hardly any CPU time, but this is not so with the much more sophisticated and functional scripts, that use a database and display dynamic content. The more individuals open this kind of a site, the more load shall be generated on the hosting server and if the database is big, the MySQL server shall be loaded as well. A good example of what can cause high load is a web-based store with a large number of products. If it is popular, a lot of people will be exploring it all at once and if they search for items, the entire database containing all of the products shall also be continuously accessed by the script, resulting in high load. In this light, having CPU and MySQL load data will give you an idea of how the website is doing, if it needs to be optimized or if you simply just need a more potent hosting solution - if the site is popular and the current setup cannot handle the load.