If Mozilla Firefox is beaten by other web browsers in any field then it is certainly the memory management of loaded websites and their components. When you visit two or more media rich websites, the Firefox browser starts to act like a big memory hog. Compared to other web browsers, Firefox seems to consume more memory for the same web sites. Most of this memory use in Firefox is related to the cache management and most of the time you do not really know how much of the memory is being used up by the Firefox cache. Thanks to the Cache Status add-on, now you can view the Firefox cache usage in real time.
You can get the Cache Status extension from the Mozilla Add-ons website. The Cache Status extension requires you to restart the Firefox web browser to finish the installation after which you can see the cache consumption in the add-ons toolbar of Firefox. If the add-on toolbar is not visible in Firefox, then you can make this toolbar visible by using the hotkey Ctrl + (press slash key while holding Ctrl key).
In the add-on toolbar, you can see both the RAM cache and the disk cache consumption for the current instance of the Firefox. You can right-click on these icons to see the options to clear RAM cache, clear disk cache or clear all type of cache. You should note that if you clear the cache, then Firefox will reload all the websites all over again.
In the options for the Cache Status extension, you can choose whether you want to display just the icons or icons with description in the add-on toolbar. You can also set a limit for the RAM cache or the disk cache in the settings. If the cache increased beyond these limits, it will be automatically get cleared, preventing Firefox from hogging down your system resources.
Conclusion: The Cache Status extension for Firefox displays the current RAM cache and disk cache consumption for the web browser. It also allows you to clear the cache and set a limit for the maximum allowable cache for the Firefox browser.
You can download and install Cache Status extension from https://addons.mozilla.org/en-US/firefox/addon/cache-status/.