The cache folder contains the copy of the websites that you have visited. Firefox uses the cache for faster loading of WebPages by taking the content from the cache instead of downloading them again from the website.
This cache folder is by default present in your user account folder. To know the default cache folder, open Firefox and then type about:cache in the address bar and hit return.
Now to change the cache folder, in the address bar type about:config and hit return. Accept the confirmation (if you enter for the first time) and then right click any one of the entries and select
New > String
Now, enter the preference name:
“browser.cache.disk.parent_directory” (without the quotes).
And then after this, in the next dialog box enter the path of the folder where you want your cache to be.
That is it, a new folder called cache will be created below the path which you have given, and the cache contents will be stored here.