Firefox has a session restore feature, which remembers what pages were opened if Firefox experiences an unexpected shutdown (read: crashes). This feature is neat, but causes many disk writes. Too many for an SSD. Disable it like this:
a. Type in the URL bar of Firefox:
b. Now you're being presented with a warning. Ignore it and click on the button “I accept the risk!”.
c. Type in the filter bar: sessionstore
c. Double-click on the item called browser.sessionstore.interval. The default interval is 15000, which means 15 seconds. Add three zeros to the existing value, so that it becomes: 15000000 and click the OK button.
d. Close Firefox and launch it again. Now you've practically disabled the session restore feature.