Firefox hangs when I open additional tabs when there are ~100 open and 1500 inactive tabs already




Tabbed Browser
2 years ago
7 months ago


(Reporter: gavenkoa, Unassigned)


42 Branch

Firefox Tracking Flags

(Not tracked)




2 years ago
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:29.0) Gecko/20100101 Firefox/29.0
Build ID: 20151104000845

Steps to reproduce:

Just open 4 new tabs via Ctrl+Click on links from Google search.

I have near 1500 tabs and 100 of them are active.

about:memory shown 5 GiB memory allocated.

I run Firefox for a long time (several days with "sudo pm-suspend") and browser rich pages (, etc).

Following report measured during Firefox hangs:

Following report measured some time later, when Firefox become responsive again:

Both report show that near 29% / 32% time spent in Timer::Fire => (JS:RunScript + JS::UnmarkGrayGCThingRecursively) and profiler shown site icons / URLs.

I assume that activity just regular JS activity on browser tabs.

I see difference in another leaf - "NM_observeActivity" call, here it is:

When Firefox hangs it spent 46% of time in that function while second report spent near 
29% in __poll call of

Actual results:

Firefox hangs for several minutes with long or no response.

Comment 1

2 years ago
Sorry, I fake **user agent** as some sites don't work with Iceweasel string.

It is no longer in Debian experimental (at 42.0-1 for AMD64), but here is old signed announce for build:


2 years ago
Component: Untriaged → Tabbed Browser
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