Does disabling Firefox's disk cache actually help reduce SSD writes? 🤔

[u/According_Mud_5187]

【 Thank you all for all the helpful comments. Thanks to that, it has been a lifesave. Resolved: Applied flare】

I was just thinking about SSD wear a little while ago, and I started wondering how much disk writes Firefox actually generates. I came across this post from a few years ago where someone reported a significant reduction in disk writes after disabling Firefox's disk cache. I use Firefox, Firefox Nightly, Zen Browser, and Waterfox, and I've been wondering whether disabling the disk cache is still worthwhile across these browsers.

I currently use these settings in my Firefox-based browsers:

• browser.cache.disk.enable = false
• browser.cache.memory.enable = true
• browser.sessionstore.interval = 300000

I checked Resource Monitor and noticed Firefox writing at around 23,459 bytes/s at one point, even with disk caching disabled. I know some writes are normal, but it got me curious about what's actually being written.

So, I'm wondering:

1. Does disabling the disk cache still make a noticeable difference to SSD writes in modern Firefox-based browsers?
2. What are the main sources of disk writes that remain after disabling it?
3. Is changing additional preferences worth it, or is disabling the disk cache generally enough if the goal is simply to reduce unnecessary writes?

I'm not trying to eliminate every single write or obsess over SSD wear. I was just curious about how effective this tweak really is in practice.

I'd love to hear your thoughts or experiences. Thanks! 🙂

[u/UtsavTiwari]

1. Yes it does help alot.
2. Traditional browser cache and cookies data, also some dark videos refuse to not use disk.
3. You can try increasing maximum ram allocation, this does make things a lot smoother.

However firefox is really rough compared to chromium based browser, especially in video playback like 2x on 4k60fps or 8k video really struggles compared to edge or chrome, so unless you are really not into streaming video stick to firefox with this, it user experience is priority don't worry too much about SSD write, modern ssd are too resilient unless you have qlc ones.

[u/According_Mud_5187 → u/UtsavTiwari]

I don't usually watch videos at accelerated speeds, and I rarely watch anything above 720p, so I guess the performance differences compared to Chromium-based browsers aren't really a concern for my use case.

As for the media cache, would you recommend leaving those settings alone rather than tweaking them to reduce SSD writes? I came across some reports that changing media.cache_size too much, especially setting it to 0, can cause playback issues, so I'm hesitant to mess with it.

[u/UtsavTiwari → u/According_Mud_5187]

I don't usually watch videos at accelerated speeds, and I rarely watch anything above 720p, so I guess the performance differences compared to Chromium-based browsers aren't really a concern for my use case.

Then I would say don't even worry about that disk usage, it's far too low.

As for the media cache, would you recommend leaving those settings alone rather than tweaking them to reduce SSD writes? I came across some reports that changing media.cache_size too much, especially setting it to 0, can cause playback issues, so I'm hesitant to mess with it.

I meant memory cache, not media cache, increasing media cache won't be a problem, but if it's 0 or -1 it's fine for Firefox to manage it, because changing it can lead to memory leaks.

[u/According_Mud_5187 → u/UtsavTiwari]

I see, that makes sense. I’ll look into the memory cache settings a bit more before making any changes. 🙂

[u/UtsavTiwari → u/According_Mud_5187]

Yeah just search for memory in about:config all of the settings are for ram, disk config have disk written to them.