CacheViewer 0.6, developed by benki, is a GUI front-end of “about:cache”, an add-on for the Firefox browser.
This plugin allows searching and sorting memory and disk cache files. A very useful tool, I installed it today.
To clear the cache, select Clear Recent History… from the Tools menu in the Firefox browser, select the desired range from the Time range to clear drop-down menu (to clear your entire cache, select Everything), choose what history elements to clear from Details and click clear now.