extending cache time / making cache last indefinitly
Hello, I have a very weak internet connection and I've been experimenting with ways to lessen the burden of the slow connection by increasing the time that the cache from websites can stay on my computer (I've already increased browser.cache.disk.capacity and set browser.cache.check_doc_frequency to 2, but the files still end up expiring eventually forcing them to be re-downloaded even though I know these cache files never change).
So far I've had some success with this extension (https://addons.mozilla.org/en-US/firefox/addon/cache-longer/) it definitely works but very inconsistently so I've tried to directly edit the cache files found in Profiles\someprofile.default-release\cache2\entries but every time I edit the max-age on the cache-control line or any other line firefox just erases the cache file completely then re-downloads it.
TL;DR - Is there someway of getting firefox to ignore the cache file expiry dates and cache-control age or at least editing these files to extend their life?
I appreciate any help in this!