I've been playing with some queries on the documentation page, and I've noticed that it's taking an abnormally long time to load even reasonably sized API call results:
On my browser (Chrome 17.0.963.56 on OSX 10.6.8, although I also tested this on Windows Chrome/Firefox latest with the same results), getting the JSON data takes about 10 msec, but displaying the results takes almost 30 additional seconds. Trying to load all the sites (ie, pagesize is some arbitrarily high number) takes minutes. During this time, the browser tab is unresponsive - I can't click on anything or scroll the page.
I don't remember it being this bad a month or so ago when I was heavily involved in writing my other applications, but it seems to have gotten worse in perhaps the last two weeks.