Open Bug 1766863 Opened 11 months ago Updated 7 days ago

Time from startup to usable tabs extremely long


(Core :: Networking, defect, P2)

Firefox 99
Windows 10



Performance Impact medium


(Reporter: jakob.kelvin, Unassigned, NeedInfo)


(Blocks 1 open bug)


(Whiteboard: [necko-triaged])

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:99.0) Gecko/20100101 Firefox/99.0

Steps to reproduce:

Use any sort-of new Firefox version up to the very latest one.
Set a custom homepage for new windows either in preferences or via GPO.
Close Firefox completely and open it up again.
Page loads extremely long - bug present.
Remove custom home page again - then bug is gone.

Problem occurs independently of what is set as the custom homepage. Also on a new profile. On all devices in at least 2 companys I know (all Windows 10 but different versions).

Bug also described here:

Actual results:

Time from when the Firefox window shows up and interaction with a tab is possible is 15 to 30 seconds. All controls can be used but everything that has to do with the content of a tab (load homepage, do a search from the address bar, open new tab and try to open some page, ...) loads very long when a custom homepage is set.

Expected results:

Browser usable immediately. Like when no custom homepage is set.

Component: Untriaged → Performance
OS: Unspecified → Windows 10
Product: Firefox → Core
Hardware: Unspecified → x86_64

I didn't manage to reproduce your issue on the latest versions Nightly 102.0a1 and Firefox 100.0.1 on Windows 10 x64.
It would helpful to know if the issue persists when changing your homepage to the default homepage or a blank page.
Also, could you please retest this using Firefox in Troubleshoot Mode to make sure that the issue is not being caused by custom settings?

Flags: needinfo?(jakob.kelvin)

The issue persists in Troubleshoot Mode. The issue happens when any kind of custom homepage is set. It doesn't matter which one. The issue does not happen when using a blank page or the default homepage.

Flags: needinfo?(jakob.kelvin)

The component has been already set for this issue. If this is not the correct component, please feel free to change it to a more appropriate one.
Waiting for the developer's opinion about it because the issue occurs on multiple devices as you mentioned in Comment 0.

There's some information here about profiling startup:

This is the profile of the startup:

Hm, that profile suggests your browser started up in 1 second, which wouldn't be bad art all, can you confirm this is from a problematic startup case?

The profile does show a bunch of very slow network requests during startup:

Looking at the markers in the parent process, I don't see a "WebExtension suspend" marker so I'm not sure what causes the slowdown.

Performance Impact: --- → ?
Component: Performance → Networking

Let's wait for the performance impact assessment before deciding on necko priorities.

The severity field is not set for this bug.
:valentin, could you have a look please?

For more information, please visit auto_nag documentation.

Flags: needinfo?(valentin.gosu)

Hi Jakob, are you still seeing this problem?
Could you try capturing a new performance profile with Settings set to Networking ?

Flags: needinfo?(valentin.gosu) → needinfo?(jakob.kelvin)

Marking S3 as it doesn't seem to affect a large number of users.

Severity: -- → S3
Priority: -- → P2
Whiteboard: [necko-triaged]
Whiteboard: [necko-triaged]
Blocks: necko-perf
Whiteboard: [necko-triaged]

I think this could have been caused by the same issue as bug 1567863 or bug 1567863, both of which have been fixed.
It may also be a duplicate of Bug 1778472.
Jakob, are you still seeing this issue?

Performance Impact: ? → medium

Redirect a needinfo that is pending on an inactive user to the triage owner.
:edgul, since the bug has recent activity, could you have a look please?

For more information, please visit auto_nag documentation.

Flags: needinfo?(jakob.kelvin) → needinfo?(edgul)

Hi Jakob,
In case you missed comment 12, are you still able to replicate this bug with the most recent version of firefox?

Flags: needinfo?(edgul) → needinfo?(jakob.kelvin)
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