This Tutorial is focused at website speed and optimization.
Optimization is an advanced topic, where a lot of technical aspects needs to be considered. This is for those of you, who just want to have the fastest loading website around.
Increasing the speed of which your website loads, will increase the usability of your site. A website which is fast, helps to give people a good impression of you and/or your company.
Website speed is often neglected, because so many people got broadband. This is not necessarily bad, but it can effect your server performance, and hence may end up effecting your users in the end.
If your hosting isn't adequate to fit your needs, your pages risk timing out, and will generally just lack vitality.
Shared hosting is more limited then dedicated hosting, and as such the performance of your website may suffer.