MockupTiger is going through some rigorous functional and performance testing. During the performance testing we found that after several forced refreshes of the pages, Firefox kept on creeping up the memory usage.
When using the Mockups, there is no need to refresh the page or the application. It is all AJAX based so the pages are pulled in the background. Irrespective of the usage, this was one test we wanted it to pass in order to provide a clean exit from the browser.
But when you keep refreshing the application main page, it kept leaking memory. This problem lead to some other bugs within the application and the browsers functionality. For e.g Why Firefox calls window.unload twice when you refresh a page or close the tab?
In our window.unload call we nullify all the objects and the DOM objects that contain the widgets. This eliminated the memory leak issue but we also had to provide a tweak for Firefox so that the cleanup is done only once.