The CPU load depends on the length of time a hosting server spends executing a script when a visitor opens a page on a certain script-driven site. Static HTML websites use barely 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 clients open this kind of an Internet site, the more load shall be created on the server and if the database is big, the MySQL server will be loaded as well. An example of what can cause high load is an online store with tens of thousands of products. If it's popular, lots of people shall be visiting it concurrently and if they look for items, the whole database containing all of the products shall also be frequently accessed by the script, resulting in high load. In this light, having CPU and MySQL load stats will provide you with an idea of how the site is doing, if it needs to be optimized or if you just need a more powerful web hosting solution - if the site is popular and the current setup cannot cope with the load.