The CPU load is dependent upon the length of time a web server spends executing a script any time a visitor opens a webpage on a given script-driven Internet site. Static HTML websites use barely any CPU time, but this is not so with the considerably more complex and functional scripts, which use a database and display dynamic content. The more people open such a site, the more load shall be generated on the web server and if the database is very large, the MySQL server shall be loaded as well. An illustration of what could cause high load is an online store with a large number of products. If it's popular, a lot of people shall be visiting it at the same time and if they seek out items, the whole database containing all the products shall also be constantly accessed by the script, resulting in high load. In this light, having CPU and MySQL load stats 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 effective website hosting solution - if the website is extremely popular and the existing setup cannot handle the load.