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Firefox engineers discover a Windows Defender bug that causes high CPU usage

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Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#51

Post by crooked-v »

stkdump wrote: post #34
boringuser2 wrote: post #21

Earlier quoted context omitted.

Firefox is significantly slower than chrome. This usually doesn't matter, but you can immediately see it in any page that A) has a massive DOM or B) uses complex regular expressions that eat up the engine

I've read that a number of times now, but I have trouble matching it to my perceptions. Can you point to a specific website where you notice that slowness and then describe what action is slower? (Initial load, clicking stuff, scrolling, etc.) Just as an example, loading jslinux.org for me in Firefox is about twice as fast than in Chrome. That might be a special case of course, because it is a very special type of wo…

Put 10,000 or so event handlers with their own DOM updates on a page. Chrome will run it smoothly (taking up a huge amount of RAM in the process), Firefox won't.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#52

Post by bobsmooth »

RcouF1uZ4gsC wrote: post #41

Is Windows Defender even worth enabling? It eats up a lot of CPU. It doesn’t seem like much help in a default update enabled system where you are using a regular user account instead of an administrator account. In addition, anti-virus and real time scanning is itself potential surface area for an exploit (for example a few years back there was an exploit based on Norton antivirus email scanner).

Enable it on your parents PC but you shouldn't need it.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#53

Post by rascul »

marcodiego wrote: post #13

> a ~75% CPU usage reduction was noted when browsing YouTube in Firefox I wonder how many of the people who say "Firefox is significantly slower than chrome" are using windows... On my computer, Firefox IS slower than chrome but (with ad blockers enabled) by an insignificant amount. By still being "the last remaining mostly independent, maintained and reasonably popular browser" I'd prefer it to use over chrome even…

I just ran a test at https://browserbench.org/Speedometer2.1/

Firefox scored 89.5 ±1.7

Chromium scored 87.3 ±2.9

I guess that means Firefox did faster for those tests. I don't use Chrome or Chromium based browsers in general so I don't know how they compare in "feel".

I am on Linux.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#54

Post by moonchrome »

jacobsenscott wrote: post #39
moonchrome wrote: post #28

This just reminds me of constant "things worked so fast on my Windows 95 machine back in the day with 16MB RAM". Meanwhile any piece of software could crash your PC and it did so regularly (I still keep spamming save in software because of those days) and internet was a pandoras box. I wonder how much overhead in modern OS/PC user experience comes from security/stability abstractions and tools.

I think it mostly comes from the fact that computers are so fast now people write apps without worrying too much about performance - apps have always grown to use whatever resources are available. But when you app had to run on a pentium with 16MB of memory - you actually had to work hard on performance because you had such limited resources.

Yes but people have this nostalgic rose tinted glasses of software from that era - it was hot garbage that crashed all the time because they had so many constraints. Yeah GC introduces a bunch of overhead - but it also means you don't get segmentation faults, memory corruption, etc.

Modern software is much more reliable than the software from that era, people nowadays complain when a button isn't working - back then a button could randomly freeze my entire PC.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#55

Post by pjmlp »

marcodiego wrote: post #13

> a ~75% CPU usage reduction was noted when browsing YouTube in Firefox I wonder how many of the people who say "Firefox is significantly slower than chrome" are using windows... On my computer, Firefox IS slower than chrome but (with ad blockers enabled) by an insignificant amount. By still being "the last remaining mostly independent, maintained and reasonably popular browser" I'd prefer it to use over chrome even…

Firefox is slower than Chrome regardless of the OS.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#56

Post by thewataccount »

ravenstine wrote: post #46

Windows Defender is a long standing bug in the Windows operating system. ;) My impression is that its invention was for the sole purpose of eradicating the idea that Windows is insecure and prone to viruses, which explains why it can be overzealous and CPU hungry. I would only enable it for family members who don't know what they are doing. For some reason, I haven't needed any form of active virus scanning in someth…

There's a misconception that you need to do something "stupid" to get a virus which is simply not the case. 0 days exist, and worms are still a thing (looking at you samba).

A great example is Pytorch just recently had a supply chain attack, and installing the nightly version between December 25th and December 30th, 2022 - would result in your home directory getting uploaded including ssh keys.

Chrome also just had a 0 day 2022 - CVE-2022-3075

Pytorch supply chain attack via Triton 2022/2023 - https://www.bleepingcomputer.com/news/security/pytorch-discl...

EDIT: Also there's a misconception that linux somehow doesn't get viruses - however the Pytorch attack affected linux users. Making a virus for windows gives you far more targets then linux, which is why they're far more common.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#57

Post by zokier »

mconley wrote: post #4

TL;DR: Windows Defender had a bug that made certain system calls expensive on CPU cycles when Defender's Real-time Protection feature is enabled. After discovery, Mozilla reported this issue to Microsoft. Microsoft is releasing a patch that should result in lower CPU usage when using Firefox on sites like YouTube (a ~75% CPU usage reduction was noted when browsing YouTube in Firefox with the fixed version of Defender…

Note that this issue is not exclusive to MS Defender, but likely all Windows AV products to varying degrees:

> > I would also like to add that this high CPU usage issue while using Firefox is not exclusive to Microsoft Defender. It's an issue for Norton's AV products also and should be the same for Symantec Endpoint products too.

> > So, you should also test them.

> It is true that we should analyze the situation with other AV vendors, however, given the numbers shared above, and given how relevant it is to keep track of memory protection changes in order to detect malicious behavior, it is very likely that the explanation for Windows Defender also applies (at least in part) to other AV vendors.

Can we get edit on the title?

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#58

Post by cptskippy »

crooked-v wrote: post #51
stkdump wrote: post #34

Earlier quoted context omitted.

I've read that a number of times now, but I have trouble matching it to my perceptions. Can you point to a specific website where you notice that slowness and then describe what action is slower? (Initial load, clicking stuff, scrolling, etc.) Just as an example, loading jslinux.org for me in Firefox is about twice as fast than in Chrome. That might be a special case of course, because it is a very special type of wo…

Put 10,000 or so event handlers with their own DOM updates on a page. Chrome will run it smoothly (taking up a huge amount of RAM in the process), Firefox won't.

What is the definition of huge amount of RAM? How does Chrome perform when it's RAM constricted? Are we blaming Firefox for poorly designed websites?

It feels like this is a straw man constructed to bash Firefox, rather than a real world scenario.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#59

Post by depereo »

JoeAltmaier wrote: post #14
consumer451 wrote: post #10

Random thought: I am not sure what the at-scale energy use reduction of this bug fix will be, but... If I had a pile of money I would consider creating a special bug bounty style program for energy use reduction. This might be a very efficient way to reduce carbon output from personal and data center computing.

Funny how that sort of thing can work out. I was involved in an industrial optimization company years ago. Microsoft came out with power-save features in their new release. The staff at a metal-recycling company we were installing at, started complaining that the furnace would stop optimizing overnight. We investigated. The controller computer would go into power-save mode, which suspended our control app. So the fur…

I found a large company was publishing windows server templates to its private cloud clients with power saving mode enabled.

The issue I was originally investigating was SQL timeouts; turned out the virtual servers were putting their virtual nics to sleep.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#60

Post by [deleted] »

crooked-v wrote: post #51
stkdump wrote: post #34

Earlier quoted context omitted.

I've read that a number of times now, but I have trouble matching it to my perceptions. Can you point to a specific website where you notice that slowness and then describe what action is slower? (Initial load, clicking stuff, scrolling, etc.) Just as an example, loading jslinux.org for me in Firefox is about twice as fast than in Chrome. That might be a special case of course, because it is a very special type of wo…

Put 10,000 or so event handlers with their own DOM updates on a page. Chrome will run it smoothly (taking up a huge amount of RAM in the process), Firefox won't.

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