The file size is definitely not the primary reason why this library speeds up your site. The fact that this tool is a single file makes it performance friendly. According to Yahoo experts, this is the first rule for making highly responsive websites. Jquery Tools

For beginners

You don't need to be a programmer to use these tools. There are lots of demos you can explore and you can copy their source code to your site and things will work. Their CSS files use minimal syntax and the crucial parts have been documented. You can use them as a template for your own work. And if you find suitable graphics you can freely use them on your site. In fact they have downloadable zip files for graphics designers that can be used as a starting point. Each tool is used in a similar manner and by learning one tool you can easily learn the other tools. Can programming be any simpler?

For serious programmers

Each tool does only what it is supposed to do and nothing else. If you want modify this default behaviour, they offer clever ways of altering and/or extending it. The API design is probably the strongest area of these tools. The design patterns are understandable. They follow the UNIX tradition of providing tools - not policy. CSS is never mixed with code. This library takes this seriously. CSS is the ultimate tool for styling - not JavaScript. And above all, the library is constantly maintained and updated. Expect to see new releases coming out on a regular basis. You are in good hands with jQuery Tools.