Performance tools for your website

Here are a couple of tools quite useful and easy to use for website performance testing.

1) iMacro
This is a great Firefox plug-in to help you create macros, and set easily testing scenarios. It is quite straightforward to add stopwatch and record results in a CSV file. See the wiki section about stopwatch feature.

2) YSlow
This firefox plugin gives a page performance report, scoring various elements of your page, and suggesting ways to improve load speed.

2) Online website stress testing.
Loadimpact.com is a great resource to test your site under stress (free version provides results for up to 50 concurrent users loading a page of your website).

Note: Yahoo has published a great page about website performance, available here. You can also have a look at this article, which provides additional information.