1120861 - Horrible Performance with many tabs open

Status: RESOLVED WORKSFORME

(Firefox :: Untriaged, defect)

Description

[Anselm Hannemann]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Firefox/38.0
Build ID: 20150112125706

Steps to reproduce:

I have about 200 tabs open, then try to visit some of these tabs, or create a new tab to load a new website.

I’ve reproduced this with no extensions, with extensions(even worse then) in a 3weeks old profile.

My setup: OS X 10.10.1 (latest), MacBookAir 2014 with 8GB RAM and i7 CPU, Firefox Stable and Nightly (v38.0a)


Actual results:

Firefox hangs for the fraction of a seconds very often, scrolling isn’t smooth anymore (actually it’s hard to call this scrolling anymore), new tabs open only after one second, website loading times are heavily impacted and take around 3-5 secs, depending on the site to load.


Expected results:

I expect the current tab I am viewing to run absolutely smooth, regarding scrolling, load times etc. And I expect tab switching to not take more than 100ms (not ~1000ms).

Comment 1

[Marco Zehe (:MarcoZ)]

Anselm, can you give any indication of whether this started happening recently, or was the case, say, in the last cycle? Can you also reproduce this with the current developer Edition (AKA Aurora)?

Comment 2

[Anselm Hannemann]

It’s different there indeed. Does it use a fresh profile? I wonder because it didn’t restore my tabs from session as Firefox Stable and Nightly do when switching to each other.

But anyway: While DevEdition is much faster, the issues still exist.

Comment 3

[:Gijs (he/him)]

(In reply to info from comment #2)
> It’s different there indeed. Does it use a fresh profile? I wonder because
> it didn’t restore my tabs from session as Firefox Stable and Nightly do when
> switching to each other.
> 
> But anyway: While DevEdition is much faster, the issues still exist.

Sorry, but now I'm confused. You mean to say that both stable and nightly are really slow, but devedition is not, with the same tabs open? (this is confusing because devedition is newer than stable and older than nightly, so it's effectively like saying it got better and then it got worse again).

Can you try using the browser toolbox's performance tool to get a cpu profile of what's happening while you switch tabs when it's so slow, to help us figure out why it's so slow for you?

Comment 4

[Anselm Hannemann]

Nah, Stable and Nightly share the same profile. I’m not sure if Dev Edition does the same as the session I have cannot be restored (it’s just not shown) in there. Therefore I had to load it via sync tool.
I’ll measure for a few hours today and will post an update here with more details. Hopefully things get a bit clearer then.

Comment 5

[:Gijs (he/him)]

(In reply to info from comment #4)
> Nah, Stable and Nightly share the same profile. I’m not sure if Dev Edition
> does the same as the session I have cannot be restored (it’s just not shown)
> in there. Therefore I had to load it via sync tool.
> I’ll measure for a few hours today and will post an update here with more
> details. Hopefully things get a bit clearer then.

That'll be helpful! To be clear, for e.g. the tab-switching slowness, the best would be a profile that you start right before switching tabs, and end right after switching tabs completes (keeping the profile running for a long time will make it harder to find out where/when there were problems).

Comment 6

[Petruta Horea [:phorea]]

Is it the same with Nightly 39.0a1? Thanks

Comment 7

[Anselm Hannemann]

Sorry for the late response. It definitely got better in 39.0a1 now. 
I think we can close this for now therefore (although sometimes I still get slow loads but not sure if that’s due to Ghostery addon because it mostly occurs when this addon is active).

Comment 8

[Petruta Horea [:phorea]]

Thanks! Let's do that for now and re-open if it reoccurs.