Sometimes a little (external) testing of your website is in order and Gagan Chhatwal has posted his list of ten tools you can use to check everything from how much load the site can take to what can be done to optimize the load time.
When maintaining or running a website , Webmasters need to keep in mind that one of the pertinent issues they will need to focus on is :Website Testing, which is not only vital for the website itself but for the user as well and one should not overlook its importance. [We have] collected some vital and free website testing tools which will help Webmasters in testing their sites thus saving users to conduct time consuming needless searches in finding the best resources pertaining to Web related tools and info.
Among the tools on the list are services like:
Most of these resources are free services, if not then they have a trial where you can see if it's a good fit.