I work on a single page web application that is ran in Firefox. The user navigates from screen to screen. Each screen is loaded via AJAX and the page is not completely refreshed until the user is done with our app. A concern our Firefox users have been having is high memory usage. I have been looking into the problem using the TabData and Tab Memory Usage Firefox extensions. The tab our app runs in appears to be freeing up memory gracefully as our users navigation from a memory intensive screen to a less memory intensive screen. However, if I view the firefox process in the Windows Resource Monitor, Firefox continues to use more and more memory and never frees it, even when I close the tab the application was running in. Are these extensions inaccurate? Is there something fundamental about Firefox's memory model I am not understanding?