The new Firefox HTTP cache back-end that keeps the cache content after a crash or a kill and doesn’t cause any UI hangs – has landed!

It’s currently disabled by default but you can test it by installing Firefox Nightly (version 27) and enabling it. This applies to Firefox Mobile builds as well. There is a preference that enables or disables the new cache, find it in about:config . You can switch it on and off any time you want, even during active browsing, there is no need to restart the browser to take the changes in effect:

browser.cache.use_new_backend

0 – disable, use the old crappy cache (files are stored under Cache directory in your profile) – now the default

1 – enable, use the brand new HTTP cache (files are stored under cache2 directory in your profile)

Other new preferences that control the cache behavior:

No longer used any new specific preferences. We are now backward compatible with the old cache preferences.

browser.cache.memory_limit

number of kBs that are preserved in RAM tops to keep the most used content in memory, so page loads speed up

on desktop this is now set to 50MB (i.e. 51’200kB)

There are still open bugs before we can turn this fully on. The one significant is that we don’t automatically delete cache files when browser.cache.disk.capacity is overreached, so your disk can get flooded by heavy browsing. But you still can delete the cache manually using Clear Recent History.

Enabling the new HTTP cache by default is planned for Q4/2013. For Firefox Mobile it can even be sooner, since we are using the Android’s context cache directory that is automatically deleted when the storage gets out of space. Hence, we don’t need to monitor the cache capacity our self on mobile.

Please report any bug you find during tests under Core :: Networking: Cache.