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

Post by thewataccount » Thu, Apr 06, 2023, 12:28 PM UTC

0x457 wrote: post #143

lionkor wrote: post #65

Earlier quoted context omitted.

windows users will also happily "run as administrator", while a lot of linux users know not to do that in my experience

Honestly...I'm far for afraid of my $HOME being uploaded somewhere. You don't need "run as administrator" for that.

Post by LtdJorge » Thu, Apr 06, 2023, 12:44 PM UTC

StillBored wrote: post #140

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 u…

Post by LinuxBender » Thu, Apr 06, 2023, 2:07 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.

Post by 0x457 » Thu, Apr 06, 2023, 9:20 PM UTC

thewataccount wrote: post #211

0x457 wrote: post #143

Earlier quoted context omitted.

Honestly...I'm far for afraid of my $HOME being uploaded somewhere. You don't need "run as administrator" for that.

> You don't need "run as administrator" for that. This is what makes it so doable since you don't need any privilege escalation. The reason why this is a big deal for a lot of people is your ssh keys will give you access to your git repos and other servers unless you have them password protected or use gpg/sk ssh keys which I think a lot of people don't do. And of course if you can see the known hosts file/bash_histo…

Post by sixothree » Fri, Apr 07, 2023, 12:10 PM UTC

cjblack wrote: post #67

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…

I'm curious how much excess energy has been consumed, and won't be consumed any longer, as a result of this improvement - even just limited to reduced CPU usage on Windows machines using Firefox to watch Youtube. I love thinking about the impacts of tiny improvements at scale like this, might do some napkin math on it later and see if I can come up with something in the right order of magnitude.