Background:**
I'm a senior software engineer running Firefox Developer Edition
on a Linux machine with 8GB RAM. I have Fission architecture
(site isolation) enabled, … (læs mere)
I'm a senior software engineer running Firefox Developer Edition
on a Linux machine with 8GB RAM. I have Fission architecture
(site isolation) enabled, which I understand is now the default
since Firefox 95+.
When I open 20 or more tabs across different domains, Firefox's
memory consumption scales dramatically — often reaching 4–6GB of
RAM for what should be lightweight browsing sessions. This is
significantly higher than what I observed before Fission was
enabled.
- What I've already tried:**
- Disabled hardware acceleration → no significant improvement
- Set browser.tabs.unloadOnLowMemory to true → partial relief
but tabs reload constantly, disrupting workflow
- Reduced content.notify.interval → marginal improvement
- Tested with all extensions disabled (safe mode) → RAM usage
still high, confirming it's not extension-related
- Checked about:memory → large number of separate
"Web Content" processes, one per origin as expected with Fission
- What I'm trying to understand:**
1. Is there a way to set a maximum process count cap for Fission
without fully disabling site isolation? I found
dom.ipc.processCount but changing it doesn't seem to affect
Fission's per-origin process spawning behavior.
2. Is browser.tabs.min-warm-process-count a relevant setting here
and what is the safe range to modify it?
3. Does Firefox have a built-in memory pressure threshold where
it automatically consolidates processes — similar to Chrome's
memory saver — and if so, which about:config keys control it?
- Firefox Developer Edition 151.0b10
- OS: Ubuntu 24.04 LTS
- RAM: 8GB
- Fission enabled: confirmed via about:support
- Extensions: disabled for testing