Firebug provides a highly detailed profiling report. It will tell you how long each method invocation takes in a giant (detailed) table.
console.profile([title]) //also see console.trace()
You need to call
console.profileEnd () to end your profile block. See the console API here: http://getfirebug.com/wiki/index.php/Console_API
Chrome’s Developer Tools has a built-in profiler.
Although Firebug has been mentioned, one additional thing you would want to look at with Firebug is a plugin for Firebug called FireUnit; John Resig talks about it in this blog post:
Hope that helps.
Firebug+Firefox is a must have. And IE 8’s developer toolbar also has a profiler built in (IE 8 ships with the developer toolbar).
Safari 4’s web inspector also includes a profiler (although the version in the nightlies is improved wrt. recursive function calls). The Web Inspector also supports Firebug’s profiler APIs.