Cascading Style Sheets make websites much more efficient because they allow the browsers to cache style-related information from the .css file directly, removing the need to read that information every time a single page is loaded. Even if Style Sheets are naturally more efficient than HTML tables you can still optimize the CSS code to make your website cleaner and faster.

I hope everyone knows this, you must optimize CSS if you want to have fast website, Speed Up Your Site: Optimize your CSS.