GTmetrix | Website Speed and Performance Optimization. GTmetrix is a free tool that analyzes your page's speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers actionable recommendations on how to fix them.
YSlow - Official Open Source Project Website. Official YSlow Open Source Project Website. YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.