Quick napkin math of the wasted power :
Firefox has ~300e6 users, let's assume the bug wasted 5 extra watts 4 hours a day.<p>That's 250 megawatts saved, the equivalent of an average coal power plant. Because some Microsoft engineer missed a bug.
> mpengine.dll version 1.1.20200.4 was released on April 4, so the fix should be available for everybody now. See the end of comment 91 to know what version you are using. Also, the latest discoveries in bug 1822650 comment 6 suggest that we can go even further down in CPU usage, with all antivirus software this time, not just Windows Defender.<p>Really nice to see open collaboration between Mozilla and Microsoft development teams resulting in a net improvement for everybody.
If you're on a Mac and using FF (probably not FF specific), turning off "ambient mode" in youtube can save 30% cpu. I just found this out while searching why FF was taking 90% of my cpu while watching youtube videos in normal mode, but went down to 40% use if viewing in full screen. Turns out that this youtube "ambient mode" was the culprit. My lap is now cooler and the fan doesn't turn on anymore. I wonder how much power I've wasted due to this new "feature" they added 6 months ago that I didn't know about.
Recent and related:<p><i>Firefox engineers discover a Windows Defender bug that causes high CPU usage</i> - <a href="https://news.ycombinator.com/item?id=35458746" rel="nofollow">https://news.ycombinator.com/item?id=35458746</a> - April 2023 (215 comments)<p>Is the current post significant new information* or just a repeat of that submission?<p>* <a href="https://hn.algolia.com/?dateRange=all&page=0&prefix=false&sort=byDate&type=comment&query=%22significant%20new%20information%22%20by%3Adang" rel="nofollow">https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...</a>
It's so frustrating this discussion took <i>five years</i>.<p>I'd be grateful for an overview of the bug. I don't think I've seen it on my two systems but I can't be confident.
That's one way to look at it, but a very biased take. An equally valid take is that Firefox was calling an expensive platform feature too often, and even though it has been killing performance for years (possibly, for the entire history of the project) nobody noticed or bothered to fix it on the application side.
When I've heard people speak of changing Web browsers in recent years, I think the two most common reasons given are performance and privacy.<p>I wonder whether this situation with Microsoft Defender cost Firefox some market share.
Interesting comment on Reddit from a Mozilla engineer: <a href="https://www.reddit.com/r/firefox/comments/12hxqjl/comment/jfs5tvy/?utm_source=reddit&utm_medium=web2x&context=3" rel="nofollow">https://www.reddit.com/r/firefox/comments/12hxqjl/comment/jf...</a><p>Careful to talk about how this is entirely a fix for Windows and will improve the experience of folks using other software, not just Firefox.
Looks like there's more work left to do to catch up to Chrome: <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1823634" rel="nofollow">https://bugzilla.mozilla.org/show_bug.cgi?id=1823634</a><p>That bug is more subtle. Apparently the various ways to use VirtualAlloc is not self evident, and some variations have wildly different performance characteristics due to undocumented interactions with Event Tracing for Windows (ETW) events that get sent to anti virus products.<p>So it's not <i>only</i> the original problem of the events being handled inefficiently, it's also that the way they're generated is a bit of a black box and hard to predict without detailed performance tracing work.
I have screamed about this like a crazy person and filed bugs and was always told, "Meh there's nothing there..."<p>But if you use Firefox to call yourself on Chrome... you'll see that Firefox takes up a TON more energy on an Intel MBP than Chrome does.<p>You can tell because Firefox literally heats your laptop up to do streaming videos. You hear the fans kick on, the laptop gets hotter to hold.<p>Anyway I'm sure there are more bugs like this! Glad Firefox is getting some of the people to fix their code... but look, Microsoft isn't the only culprit. Until Firefox takes as little power as Chrome in MacOS & Windows... I think we should all stay outraged! (=
Good thing its a bug though, not a monopolistic attempt to sabotage the competition running on your platform, by doing strange things with API rodeo. This surely ruined the performance of other software too..
Guess that's why I never feel firefox laggy but others said it is. The first thing I do after installing windows is always installing some other antivirus to disable defender. Because the defender start routine scanning at weird time and lag games randomly, which is really annoying.<p>I really have no clue why engineer at ms think such behavior is ok. Shouldn't scans like these scheduled at some time slot that people are not actively using computers?
I would like anyone that considers Microsoft to be a recent champion of Open Source to reflect on corporate doublespeak. It's plausible that this bug was engineered as an attack on Firefox.
yet another reason why I don’t touch Windows for any professional/sensitive workflows.<p>Only keep a license around for the occasional gaming session. Disable all of the Windows features (ie, firewall, auto updates, antivirus) and telemetry. Strip the OS to bare minimum and manage the GPU, mobile drivers manually. Limit it to only games