Fenix: [Bug] Fenix is unusably slow

[evilpie]

Steps to reproduce

• Go to google.com
• Enter Hacker News
• Goto news.ycombinator.com

Expected behavior

Loads in 1-2 seconds max.

Actual behavior

Loads for ~15 seconds, hangs, app unresponsive.

Device information

• Android device: 9
• Fenix version: Nightly 200210 GV: 74.0a1

Additional Information

I just got updated from Firefox Nightly (Fennec) to Firefox Nightly (Fenix). I sadly now have to abandon using Nightly because it's unusable. I am attaching a screen recording. I will try to run a profiler if possible.

Videos: https://drive.google.com/drive/folders/18GtTuhNAqa1UutcQb7_PsnG3weQDLqPp?usp=sharing

[abodea]

Thank you for this report @evilpie!

Note that I tried to reproduce this issue but I wasn't able to.
I updated from Firefox Nightly(Fennec) to Firefox Nightly(Fenix), note that I followed the steps from the description and the Hacker news website loaded in 1-2 seconds after the update.

I used Samsung Galaxy S10+ (Android 9), can you specify exactly what device are you using?

[evilpie]

Samsung Galaxy S8

[ecsmyth]

Unable to reproduce on:

• ZTE Maven running Nightly build 20440605
• Samsung Galazy S10 Intl build 20440606

@evilpie, if you're able to reproduce consistently, could you grab a profile to help us investigate?

[evilpie]

Here you go: https://perfht.ml/2uL4VhD

This is using a slightly different STR, I directly entered news.ycombinator.com in the address bar, but the issue still reproduces.
The profile seems to indicate to me that for a long time we are basically not doing any work?

[ebalazs-sv]

Hi!
I tested this on Nightly Migration Build 02/10 with Samsung Galaxy S8 (Android 9) and I wasn't able to reproduce the issue.
Video

[csadilek]

@evilpie looking at your profile, it seems you have uBlock enabled. Can you try disabling it (Settings->Addons) and see if the problem is still reproducible? To make sure you're not running into this case: https://github.com/mozilla-mobile/fenix/issues/8251

[evilpie]

After removing uBlock I had a single instance where the load took 2-3 seconds, but now it's back to being slow.

https://perfht.ml/37tEYjU

[yaomtc]

Twitter has had issues with slowness/unresponsiveness, where sometimes just hitting the back button (on a Twitter thread, not the system back) takes several seconds to do anything at all, and if I tap it again it ends up opening the Account Info sidebar a moment later as if I clicked on my avatar that wasn't yet visible...

[boek]

Closing as a dup of #7903