I don't like filling up my backup file for reasons of both performance, & on flash drives, to minimize the number of writes to the drive. For this reason it is important to get Firefox under control, as it is one of the biggest offenders.
I use a two-fold approach to this: create the default user profile in a persistent opt directory, and turn off disk caching in the firefox configuration.
(I use only Namoroka from the tcz repo as I have had too many problems with mainline firefox, but the same method applies to both.)First:
Create a directory in opt owned by tc/staff
where you will put your firefox profile. You can just name it firefox or namoroka.
: Do a clean install of Firefox/Namoroka, and go into the profile manager before
you open firefox for a first-run.
[This is important to keep it from creating the default profile in home/tc]
$ user/local/namoroka/firefox -ProfileManager
$ user/local/firefox-official/firefox -ProfileManager
The profile manager should show no
profiles have been created yet.
Let your profile be called Default User as it suggests, but choose your own folder to place it in, and browse to the location of your created firefox folder in opt.
(This will create a .mozilla folder in home, and a profile.ini, but everything else will go to opt.)
On first-run of firefox, go to about:config, promise to be careful, and type cache in the search box.
Go to the line browser.cache.disk.enable, right click on it, and click toggle.
[NB: This step is only important for usb flash drives or ssd drives where the number of writes to the disk needs to be minimized]
That's it. It works really well.
I've run into some instability when I had gazillions of add-ons installed, but decided the solution was to cut back on the add-ons ;-)
Long-life to your flash & ssd drives!