I also see a memory leak with JQuery ajax jsonp requests. I have observed the leak in IE, FireFox and Google Chrome. I would like to request that the priority of this bug be increased.
A reduced test case is provided at http://jsfiddle.net/G2kq8/3/show. This sample code makes repeated calls to the //jsfiddle.net/echo/jsonp echo api to demonstrate the memory leak that occurs when you repeatedly load large chunks of data with jsonp in JQuery. To isolate the problem, the code doesn’t process the data it receives; it just repeatedly requests the data and updates a counter on the HTML page. This test case is similar to http://jsfiddle.net/danheberden/jU2VG/5/, but demonstrates the problem a little more dramatically by loading a larger data block in each request.
The browser’s memory usage will continually increase while this example is run. The memory will not be freed until the page is refreshed. If allowed to run continuously all of the memory on the PC is consumed by the browser in a matter of hours. The browser will periodically perform garbage collection, and the memory usage can be seen to decrease occasionally, but it always decreases to a memory level higher than that achieved at the last garbage collection.
This example has been demonstrated to leak in Internet Explorer 8 (Specifically 8.0.6001.18702), Firefox 8.0 and Chrome 15.0.874.121. Firefox was run in safe mode, IE was run with third party extensions disabled, and chrome was run with no extension. Most of my testing was done with Firefox. The leak appeared to be most pronounced in Firefox.
This example has been demonstrated to leak using jQuery 1.7.1, jQuery (edge), and jQuery 1.2.6.
My Operating System is Microsoft Windows XP Professional, Version 2002, Service Pack 3.