1283878 - [codeacademy.com] Firefox hangs

Status: RESOLVED WORKSFORME

(Firefox :: Untriaged, defect)

Description

[alemcnurlin]

Steps to reproduce:

* Visit www.codeacademy.com (this happens on other websites, however codeacademy is the one that does it every time on the homepage)
* Note that all open instances of the browser hang and become unusable for about 10 seconds.
* Disable Javascript in the developer tools
* Reload the page and note that the page loads without any problems

Using Ubuntu 16.04. This started happening after the upgrade from 15.04 to 16.04. This issue persists after completely uninstalling firefox and reinstalling.

After the hang occurs, the following text appears in the javascript console: "Prefixed Fullscreen API is deprecated. Please use unprefixed API for fullscreen. For more help https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API"

Comment 1

[:Gijs (he/him)]

Needs triage, moving to untriaged.

Comment 2

[Gérard Talbot]

alemcnurlin,

> the following text appears in the javascript console: "Prefixed Fullscreen API is deprecated. 
> Please use unprefixed API for fullscreen. For more help 
> https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API"

This is a warning, a notification. It probably is not related to the hang.

How to Report a Hung Firefox
https://developer.mozilla.org/en-US/docs/Mozilla/How_to_report_a_hung_Firefox#Linux_and_Mac

- - - - - - 

I visited www.codeacademy.com with a Firefox nightly (version 50.0a1 buildID=20160701121753). The browser became indeed unresponsive for about 10 seconds but, after such about 10 seconds, it became responsive. That webpage has multiple style sheets and scripts with unbelievable amount of code. One style sheet alone

https://s.ytimg.com/yts/cssbin/www-embed-player-vfl9PJiTO.css

has 1609 rules and over 9000 lines of CSS code. So, I am not surprised if your browser - or any browser - hangs for 10 seconds.

Comment 3

[Adrian Florinescu [:aflorinescu]]

Gerard, alemcnurlin, I did try the above site(www.codeacademy.com) with my ubuntu 16.04, but I didn't experience the reported freeze behavior. I might say that the initial load takes somewhere under 1s, but nothing as extreme as hanging 10 seconds.
I used latest release and nightly:
       Version	47.0 Build ID  20160606113944
       Version 50.0a1 Build ID 20160703030210

Comment 4

[Gérard Talbot]

The site www.codeacademy.com (at least the entrance page) changed since I visited it. We can assume that the site changes on a daily basis. The site is also very much ad-driven and intensively driven by javascript and very detailed and long style sheets. So a delay of a few seconds can exist if the user has modest memory resources but we can not reproduce an application hang. Therefore,

I am resolving this bug as WORKSFORME