Try this link to get you started: click here
It gives you loads of options and feedback for pretty much everything: browser compatability, accessibility, download time on all connection speeds, hyperlink verification and all kinds of other nice things get a thorough going over.
click here has software to use on your own system, at a significant cost, and it is really meant for professional use.
Try the Cool Tools link on this site click here for another readout at 56k.
The one I often use is WebSlower: click here
WebSlower is free, it tests your page[s] at all connection speeds and is pretty accurate in its results. I rather like it.
There are lots of other alternatives but the above should set you on the right track.