One important thing about designing website is speed. There’re many tools that help you measure your site speed, but this tool is an online tool. I tried this tool and impressive.
GTMetrix is an online tool that measure your site performance and speed and grades of performance on your site. GtMetrix also gives you the info on what are the causes of your good and bad performance. My Site got D on YSlow and C on Page Speed, very very bad 
GTmetrix uses Google Page Speed and Yahoo! YSlow to grade your site’s performance and provides actionable recommendations to fix these issues.
Link : gtmetrix.com
