We all agree that performances (loading speed, UI responsiveness, etc.) are important for a website. The speed of pages has a big influence on User Experience. Nowadays with the proliferation of mobile devices, performances have a big impact in term of cost too: the price of mobile plans are based on how much MegaBytes are downloaded/uploaded.
Improving website performances is not easy and it is time consuming. We have to remember that a web application has two sides: the server side and the client side. Of course, both must be optimized, but in this post I discuss about some tools to optimize the client side.
At the moment, Google Page Speed is one of the most complete tool that analyzes a page, finds which are the weak points and suggests how to correct problems.
Like HTML, also CSS files could be minified and optimized. Useful tools are: YUI Compressor and sCSSors (this is a tool created by me and no longer mantained).