I know everyone who reads the question will think \"Firebug!\" right away. Maybe some will think \"YSlow!\" and \"Google Page Speed!\"
While I really like these tools, I
WebWait works in any browser.
It's yet another tool to have in your web performance utility belt.
You can use the IE high performance tester.
I don't pretend to know the absolute answer. But one method would be:
While this may not be a completely satisfactory answer, I will observe that this is the easiest.
By the way, what do you think are the performance aspects that you can highlight using a "browser level test" that you can't with a "firebug level test"?
Cheers,
jrh
I am not sure it is a useful endeavor to optimize for only one vendor:
You can get Firebug for IE (and Opera and Safari):
http://getfirebug.com/lite.html
Put a script block at the beginning of the document, at its end and set window.onload. Grab the current timestamp via Number(new Date) at each of these 'sequence points' and you can get a first impression of how long the page needs to render in a browser-agnostic way.