Limiting disk write actions of Firefox

idem for all forks , such as LibreWolf

put Firefox network cache into RAM

• less disk writes.
• probably faster Firefox
• The price : 512 MB RAM.

Procedure
- type in the URL bar about:config
- type in the filter bar (search bar): browser.cache
- browser.cache.disk.enable : toggle value to false by double-clicking it: this will disable “cache to disk” entirely.
- browser.cache.memory.enable : should already be  true; if not, toggle it to true 
- browser.cache.memory.capacity : entry should exist (if not, create it first)
-  integer value will probably be -1, which set the maximum size of the RAM cache as dependent on the available amount of RAM.
this automation usually creates a cache that’s too small.
- set it to 524288 (KB, which equals a maximum of 512 MB). Usually enough . But if you have RAM to spare, use  1048576 (= 1 GB) .
- close Firefox and restart.
- check n the URL bar: about:cache

Disabling sessionstore

session restore remembers what pages were opened if Firefox experiences an unexpected shutdown
This feature is neat, but causes many disk writes.

Procedure
- type in the URL bar about:config
- type in the filter bar (search bar): sessionstore
- . Double-click on  browser.sessionstore.interval
The default interval is 15000 (15 seconds) . Add three zeros to the existing value, so that it becomes: 15000000 and click the OK button.
- restart Firefox and launch it again.
Now you’ve practically disabled the session restore feature.

Notes 
- Leave the other cache and sessionstore settings as they are: usually, the less invasive a hack is, the better. Because this reduces the risk of unexpected unwanted side effects.
- These are user preferences. Repeat this hack in each user account.