NexBrowser Türkçe
Memory

We measured it and wrote the results down as they are.

All three browsers were opened on the same computer, with an empty profile and the same 8 sites. Numbers use PSS, which splits shared memory between processes, so a browser cannot hide behind many small processes.

Right after launch

Total memory of all processes 60 seconds after opening the 8 tabs.

NexBrowser 1,476 MB
Zen 1,698 MB
Firefox 2,403 MB
BrowserMemory (median)RangeProcesses
NexBrowser13% less than Zen 1,476 MB 1,404–1,493 12
Zen 1,698 MB 1,682–1,707 36
Firefox 2,403 MB 2,324–2,425 46

When tabs sit idle

The same 8 tabs, then another 150 seconds of waiting. For this test NexBrowser's tab sleep timeout was lowered from 20 minutes to 1 minute; nothing changed in the other browsers.

NexBrowser 596 MB
Zen 1,629 MB
Firefox 2,408 MB
BrowserMemory (median)RangeProcesses
NexBrowser63% less than Zen 596 MB 584–631 8
Zen 1,629 MB 912–1,638 35
Firefox 2,408 MB 2,387–2,680 49

Method

  1. Sites: Wikipedia, GitHub, YouTube, Hacker News, MDN, BBC News, Stack Overflow, The Verge.
  2. Every run used a new, empty profile; welcome screens were turned off.
  3. Memory is the PSS sum of the whole process tree starting at the browser's main process.
  4. Each browser was measured 3 times; the table shows the median and the min–max range.
  5. Runs were sequential, never two browsers at once.
  6. Versions: NexBrowser (based on Firefox 159), Zen 1.23.4b (based on Firefox 158), Firefox 153 ESR.

Changed preferences

All of them can be reverted in about:config.

  • fission.webContentIsolationStrategy1 2
  • dom.ipc.processCount8 4
  • dom.ipc.processCount.webIsolated4 1
  • dom.ipc.processPrelaunch.enabledtrue false
  • browser.tabs.unloadOnLowMemoryfalse true
  • browser.low_commit_space_threshold_percent5 10
  • browser.tabs.min_inactive_duration_before_unload600000 300000
  • browser.sessionhistory.max_total_viewers-1 2
  • image.mem.surfacecache.max_size_kb2072576 524288
  • network.prefetch-nexttrue false

What these settings cost

Memory is not free. Here is what we changed and what changes in return.

Site isolation

Firefox gives every site its own process. NexBrowser isolates only sites you are signed in to and high-value sites; the rest share processes. If a site is compromised, the risk of reaching data of another site in the same process is higher than in Firefox.

Tab sleep

When you return to a sleeping tab the page reloads; an unsaved form may be lost. You can change the timeout or turn the feature off in about:config.

Back/forward cache

At most 2 pages are kept in memory for the back button. Going further back reloads the page from the network.

Prefetching

"Next page" hints from sites are ignored; on some sites the next page can open a moment later.