1682187 - Loading reddit after starting Firefox is delayed for a minute

Status: RESOLVED WORKSFORME

(Core :: Performance: General, defect, P3)

Description

[Asif Youssuff]

From: https://www.reddit.com/r/firefox/comments/kbwrl7/first_reddit_load_after_starting_firefox_takes_1/

Basic information

I'll start firefox, reddit homepage won't load, navigating manually to any reddit URL just hangs on a white screen. After a minute or so, it loads and all subsequent page loads are quick.

If I see it happening, I can close firefox and re-open it and there's a 50/50 it happens again or works right away. This indicates to me some sort of load balancing taking me to a bad endpoint but I don't think it's DNS, at least not on the part of Windows as I've tried modifying my network adapter's DNS servers with no effect.

Steps to Reproduce:

Expected Results:

Actual Results:

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More information

Profile URL: https://share.firefox.dev/34aoqPo

Basic systems configuration:

OS version: Windows 10

GPU model: NVIDIA GeForce GTX 1070

Number of cores: 6

Amount of memory (RAM): 16GB

Thanks so much for your help.

Comment 1

[Asif Youssuff]

Attachment: about:support

Comment 2

[Mike Conley (:mconley) (:⚙️) (PTO Dec 22 - Jan 2)]

Hey Asif,

I looked at the profile. It's missing the content process, but from what I can glean from the Network pane, we're spending a long time waiting for the Reddit server to respond.

Do you get similar behaviour with other browsers on that machine on that network?

Comment 3

[Markus Stange [:mstange]]

It might be related to service workers. In the profile, I can see https://www.reddit.com/sw.js loading just before the eventual "real" load to https://www.reddit.com/r/all/ happens. But something delays that request to https://www.reddit.com/sw.js.
I don't see any long-running "Extension Suspend" markers, so extensions don't seem to be at fault here.

Asuth, how can we narrow down what happens here?

Comment 4

[Asif Youssuff]

The user in the reddit post said in their first post:

Chrome has no such behavior and works fine every time.

Comment 5

[Olli Pettay [:smaug][[e-mail]]]

Do you think it would be possible to get more profiling here? Worker threads at least and the relevant child process

Comment 6

[Asif Youssuff]

The user says that they no longer see this issue.