I want something to measure a website's performance that's free and doesn't require any changes to become designed to the code (jsp asp pages). All assistance is appreciated.
For performance measurement I suggest you YSlow, it is a Opera add-on integrated with Firebug, it evaluates your webpages and informs you why they are slow in line with the rules for high performance web sites.
Also using the Firebug Network Monitoring tab, you can observe which assets take additional time and bandwidth to download:
Another solutions for this question concentrate on performance of merely one user from the site using their browser's perspective. If you wish to test the performance of the server, for instance, to determine the number of concurrent customers you are able to support, you have to be searching at tools like JMeter.