A month ago, the search engine giant , Google announced that Website Pagespeed is going to one of the parameter for PageRank(PR) . You need to know that page loading time does not attract the visitors but allows visitors to stay on the page rather than closing the webpage if your website loads slower.
There are many website where you can check your website speed, even Google has one .
* Google’s PageSpeed – http://code.google.com/speed/page-speed/
* Yahoo YSlow – http://developer.yahoo.com/yslow/
Although there are many website online which provides these service, i came across GTmetrix which help you to test without downloading Pagespeed or YSlow add-on.
You can see the reports online and modify the elements in the website that loads slower. It also gives you a grade according to YSlow and PageSpeed. You can register for free and compare the test result with Time frame. You can also set a daily / weekly /monthly speed check. Here is a test sample :