Firefox engineers discover a Windows Defender bug that causes high CPU usage • Hacker News Board

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

#131

Post by bob1029 » Wed, Apr 05, 2023, 11:35 PM UTC

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.

> for energy use reduction

This can be a dangerous objective. There are already changes going into Windows 10+ regarding the OS scheduler [0]. Windows 11 is also noted as having an even more aggressive policy. How much longer before old games stop working correctly and we have to have MS-signed binaries to get 1ms timer resolution?

Obviously, we don't want to poll aggressively whenever we can avoid it, but there are also a lot of practical UX & technological reasons to have this capability.

[0]: https://learn.microsoft.com/en-us/windows/win32/api/timeapi/...

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

#132

Post by dylan604 » Wed, Apr 05, 2023, 11:40 PM UTC

olyjohn wrote: post #91

dylan604 wrote: post #40

Earlier quoted context omitted.

I've noticed that AWS Console will spin up the fans on my MBP running Firefox, specifically on the EC2 screen. None of the other Console screens spin up the fans like that. Viewing about:performance always shows the AWS tab running full tilt to the point I've jokingly assumed they're trying to spin up an instance via WASM ;-)

The "new" EC2 console is the biggest pile of crap.

it amazes me how they can release that kind of thing. something the size of AWS, and this is what gets released to the public?

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

#133

Post by pixelbath » Wed, Apr 05, 2023, 11:41 PM UTC

rascul wrote: post #53

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.

Interesting. I get 362 ±15 running Vivaldi (Chromium-based) M2 Macbook Air.

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

#134

Post by bloaf » Wed, Apr 05, 2023, 11:48 PM UTC

rascul wrote: post #53

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.

My old android phone got 52.7±2 chrome, 51.6±0.8 in Firefox, so effectively the same.

However, I had to disable some ff add-ons to get that score (chrome had no add-ons to begin with).

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

#135

Post by SSLy » Wed, Apr 05, 2023, 11:59 PM UTC

ivanmontillam wrote: post #49

Cthulhu_ wrote: post #37

Earlier quoted context omitted.

> I purchased a license of a proper antivirus software Which is that? For years (and come to think of it, this goes back to the 2000's or even 90's), AV / antimalware software comes across as scareware, using tricks to ensure you're afraid of not having it. And second, who here has ever had a virus in the past ten years?

> Which is that? I purchased a license of ESET Internet Security, and full disclosure: back in early 2017, I worked at an ESET-licensed reseller as a Presales and Support Engineer, so I know how to fine-tune it and all the ins and outs. By nature, it's very lightweight (330 Mb RAM footprint), but you can fine-tune it even more if you want. > And second, who here has ever had a virus in the past ten years? We the peop…

You can't leave us without sharing the nod32 tuning tips

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

#136

Post by ricardobeat » Thu, Apr 06, 2023, 12:02 AM UTC

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’ve noticed Firefox getting unbearably slow when several YouTube tabs were open. Tried toggling HW accel too with no success. Yes, I did blame FF since thorium (the chrome variant I use) doesn’t suffer from the same problem.

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

#137

Post by prepend » Thu, Apr 06, 2023, 12:09 AM UTC

I’ve found many of these bugs and defender would frequently peg cpu and I’d have to disable it.

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

#138

Post by initplus » Thu, Apr 06, 2023, 12:20 AM UTC

Biggest headache with Windows Defender is it's abysmal single threaded IO bottlenecking. Writing large number of files to disk? Windows defender will be busy slowing down every single one of those writes as it scans... wouldn't be so bad if it didn't do so on a single thread. I have 10 cores, use them!

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

#139

Post by genocidicbunny » Thu, Apr 06, 2023, 12:22 AM UTC

jbritton wrote: post #125

Yoric wrote: post #85

Earlier quoted context omitted.

In my experience (as a former Firefox dev), antivirus / antimalware software are really poorly behaved. They tend to: - require admin rights (which means that if they have vulnerabilities, it can take control of the entire machine, even if Firefox itself is sanboxed); - monkey-patch the Firefox executable in memory, which works (when it does) as long as the version of the software tracks closely the version of Firefo…

I had always assumed that one application could not touch the memory of another application. Does running as Admin allow breaking this boundary?

Yes, in general on Windows processes with higher privilege levels can get access to read/write another processes memory, or even inject code into them. And even Admin-level processes can still be broken into by something running as a service with even more elevated privileges like NT AUTHORITY\SYSTEM.

This has long been a leaky part of Windows security. If your malware can get its code running inside a highly privileged service or process, it can do more or less whatever it wants to the rest of the system. But even when not used for nefarious purposes, it is still an extremely dangerous capability in that it can be very easy to create problems .

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

#140

Post by StillBored » Thu, Apr 06, 2023, 12:33 AM UTC

Well, windows defender is the single largest CPU hog Ive found on these low end cherry trail/silvermont/goldmont/etc tablets.

Particularly when windows update kicks on the CPU's go to 100%, the thing overheats, and generally is absolutely unusable as it downloads and scans/etc the update its preparing. The devices go from usable but slow, to put it down for a couple hours cause you won't get anything done levels of usability.

Disabling windows defender for the 24 hours (or whatever it takes) before windows decides to turn it back on, is the single largest performance hack I've found to make those devices run reasonably. Guess this "bug" just reinforces that fact.

Maybe someone should donate a few to MS's windows engineering teams so they can enjoy the monster they have created running on the low end hardware that is still being sold.