1557158 - Firefox incredibly slow in site

Status: RESOLVED DUPLICATE of bug 1475013

(Core :: DOM: Core & HTML, defect, P5)

Description

[João M. S. Silva]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:67.0) Gecko/20100101 Firefox/67.0

Steps to reproduce:

Access https://www.particulares.santandertotta.pt/pagina/indice/0,,276_1_2,00.html

Actual results:

Firefox gets extremely slow.

Typing in text boxes takes several seconds to show the characters.

Everything is slow.

Expected results:

Normal user interface, responsive.

Comment 1

[João M. S. Silva]

I tried restarting with all plugins/addons disabled and the behavior is the same.

I looked at Firefox's task manager and it indicates no problems at all with this tab.

Chromium has no problem with this site.

There are other users observing the same: https://support.mozilla.org/en-US/questions/1260770#answer-1227489

Comment 2

[Alin Ilea, Desktop Test Engineering]

Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:67.0) Gecko/20100101 Firefox/67.0

Hi,

I have managed to reproduce this issue on latest FF release (67.0.1) and latest Nightly build 69.0a1 (2019-06-11) using Ubuntu 18 and Windows 10.
After a while the site get froze and I get this error message:
"A script on this page may be busy, or it may have stopped responding. You can stop the script now, open the script in the debugger, or let the script continue."

I will move this over to a component so developers can take a look over it. If is not the correct component please feel free to change it to an appropriate one.

Thanks for the report.

Comment 3

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Hi Alin Ilea,
Could you please help get profile for us by running Firefox Profiler? That can make this more actionable. Appreciated!
https://profiler.firefox.com/

Comment 4

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

The page seems to be running heavy setIntervals all the time
https://perfht.ml/2ZOOzyj

Comment 5

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

João, could you perhaps contact the website, this looks like an issue on their side.

Comment 6

[John Dai[:jdai]]

According to comment #5, it looks like a website issue. I'll close this bug. Feel free to reopen it if it's still valid to you. Thanks.

Comment 7

[João M. S. Silva]

It may be a problem with the site, but how come Chromium does not have any problem displaying the page?

Today it's still slower in Firefox, a few minutes until page is loaded.

Comment 8

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

The website is doing something unexpected with setInterval.
Extremely deep callstack underneath.

Mike, do you know who could help here?

Comment 9

[Mike Taylor [:miketaylr]]

Tom, could you take a look please?

Comment 10

[Thomas Wisniewski [:twisniewski]]

This site doesn't want us debugging their page at all. They use debugger keyword injection and their scripts are obfuscated to a malware-level degree (in fact I see malware may have used the same library, searching around for debuggerProtection(0x0)).

As per the general rules of karma, it seems as though that same obfuscated code which is trying to defeat debugging is what's causing these performance issues on Firefox. When I save a local copy of the page and early-return from the four or five spots which are doing the debugger-keyword-injection, the problem seems to go away.

The technique being used is the function(){}.constructor("debugger")() method, using code like this:

(function() {   
  return ![];
} ['constructor']('debu' + _0x15f5('0xb6', 'x#lw'))[_0x15f5('0xb7', 'Dzcq')](_0x15f5('0xb8', '@Q*F')));

(function() {
    return !![];
} [_0x3a6d('0x943', '@x3s')](_0x3a6d('0x944', '^lIo') + 'gger')[_0x3a6d('0x43e', 'qHvK')](_0x3a6d('0x945', '^lIo')));

So this seems to share the same underlying cause as bug 1475013.

Curiously we did better on this before something in this Mozregression range, but I can't easily spot what might have been the cause:

13:16.01 INFO: Last good revision: 179dae92e4d794e7f45ad080ff01908c80691f31 (2017-11-06)
13:16.01 INFO: First bad revision: 40df5dd35fdb7ce3652fe4448ac8961c075c928e (2017-11-07)
13:16.01 INFO: Pushlog:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=179dae92e4d794e7f45ad080ff01908c80691f31&tochange=40df5dd35fdb7ce3652fe4448ac8961c075c928e