The CPU load depends on the time period a web server spends executing a script whenever a visitor opens a webpage on a certain script-driven Internet site. Static HTML sites use hardly any CPU time, but this isn't the case with the significantly more complex and functional scripts, which use a database and display dynamic content. The more people open this type of an Internet site, the more load shall be generated on the web server and if the database is large, the MySQL server shall be loaded as well. An illustration of what may cause high load is a web-based 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 that 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 needs to be optimized or if you simply need a more effective hosting solution - if the website is extremely popular and the established setup cannot deal with the load.