TenFourFox and SSD's


macrumors 6502a
Original poster
Oct 21, 2015
(UTC-05:00) Cuba
Firefox and therefore TenFourFox are hard on SSD's because of the frequency and amount of data that it caches (ie: writes to disk).

The cause of this activity is the frequency that open pages are saved to disk - the saved information is used to recover open pages in the event that Firefox crashes. By default every page / tab that's open is written to disk every 15 seconds, regardless if the page has changed (since the last write) or not.

Two options to reduce SSD wear are (1) change the interval information is saved and (2) move the save location to a different location (ie: spinning hard drive).

Option 1 is documented in this post -> LINK.

Option 2 - move the save location is documented below:

Firefox stores the open page caches in the Firefox profile directory. In the ~/Library/Application Support/Firefox directory there's a profiles.ini file. One of the lines in profiles.ini, IsRelative, tells Firefox if the profiles path is relative or independent of where the profiles.ini file is located. By default it is relative and set to one (1). By changing this to a zero (0) and editing the line beginning with Path to a valid fully qualified path you can relocate Firefox's profile.

Here are copies of the relevant lines from my original and edited profiles.ini file:



Important Note

You need to manually copy (or move) your profile directory to the new location. If you don't Firefox will create a new profile and none of your customization (add on's, settings, tweaks, etc) will be used. In case you forget to move your profile directory simply shutdown Firefox, delete the new profile directory then copy / move your profile directory.


macrumors Core
Aug 31, 2011
ten-zero-eleven-zero-zero by zero-two
Just one thing to be cautious about. If you move your profile directory to an external disk or flash drive you'll need to make sure that drive is connected whenever you are using T4Fx.

I used to have my profile on a USB stick and there were times I forgot to put the stick back in when I went back to the laptop. I had a number of issues because of this.


macrumors 6502a
Original poster
Oct 21, 2015
(UTC-05:00) Cuba
Because I use this on a G5 with dual drives (SSD - boot, spinning - temp / cache) using removable media hadn't crossed my mind.

Thanks for mentioning that Erik.
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macrumors 68000
Oct 21, 2015
Kiel, Germany
Many thanks for that hint!
It's crazy and hard to believe, that amount of data is squeezed through the web for nothing but convenience.
Firefox is running on millions of computers - what a waste of energy!
I've set the saving time now to 1h ... curious if I'm going to note any difference!?
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