A performance-sapping battle between Mozilla Firefox and Microsoft Defender was first mentioned on Bugzilla half a decade in the past. Nevertheless, Firefox customers can now rejoice, as Mozilla devs and Microsoft labored collectively to launch an replace to MsMpEng.exe (a core technique of Home windows Defender), which is at the moment being rolled out. Troubled customers ought to discover a important enchancment (opens in new tab) after the replace, with “a ~75% enchancment in CPU utilization from MsMpEng.exe when shopping with Firefox,” in response to senior Mozilla software program engineer Yannis Juglaret.
So, what has been taking place, and why was there an terrible interplay between Firefox and Microsoft Defender? Microsoft acknowledged an issue with MsMpEng.exe utilizing an excessive amount of CPU time when Home windows Defender’s real-time Safety function is spurred into motion. This alteration has helped lower the CPU utilization noticed by Firefox customers considerably.
The Firefox app was notably arduous hit by the Microsoft bug, because the browser is alleged to generate as much as 7x extra Occasion Tracing for Home windows (ETW) occasions in comparison with rivals (Edge, Chrome and many others). It sends these ‘VirtualProtect’ calls to the antivirus / anti-malware supplier to attempt to maintain the browser secure from hurt because it roams the net.
Although Microsoft’s patch of MsMpEng.exe helps so much, as you possibly can see from the above-quoted figures, Mozilla devs acknowledge that “We should always attempt to cut back the variety of occasions that Firefox generates, which can cut back the CPU utilization from [all] AV software program.”
With this in thoughts, additionally it is price noting that different AV options, like these from Norton, may also devour a whole lot of CPU time as a result of quite a few (7x) Firefox requires monitoring VirtualProtect. Thus, any program that calls VirtualProtect will profit from Microsoft’s new MsMpEng.exe, not simply Firefox.
An “Explosive” Waste of Time
Mozilla’s Juglaret summed up the prior state of affairs most succinctly when he wrote (opens in new tab), “This drawback has two sides: Microsoft was doing a whole lot of ineffective computations upon every occasion; and we’re producing a whole lot of occasions.” He then underlined the influence, “The mix is explosive.”
Utilizing extra processing energy than mandatory is a typical irritation for laptop customers. These utilizing laptops away from an influence outlet will need to keep away from CPU-eating purposes when there are extra environment friendly alternate options. In the meantime, if the issue is widespread sufficient and runs lengthy sufficient, the mathematics can also be scary for desktop customers. For instance, Hacker Information discussion board members have estimated the power wasted by Microsoft’s MsMpEng.exe, and the 300M+ customers of Firefox may have simply eaten up all the output of a median coal-fired energy plant each day…