Ever wonder if your change is going to slow down the website? "Performance impact will probably be negligible", you might say. Well, now you can know for sure. First, take a slice of your production logs and transform it into a particular format. Then run ReReplay with this snapshot to generate a baseline. Next apply your change, rerun ReReplay (sorry, too many re's?) and measure the difference!
So we made an interesting discovery these past days...IE handles some redirects in AJAX really, really badly.
This table explains:
|To itself||To another page|
|FF||Redirect 18-20 times||Didn't test|
|IE||Redirect until you close the browser||Redirect 10 times|
(By "redirect to itself" I mean you have some bug in your logic such that page http://example.com/?page=1 will redirect to itself indefinitely.)
Do you like that "redirect until you close the browser" one? Even if you go to a completely different site, the browser will still be making requests to yours.
Moral of the story: be very careful with redirects with AJAX.