Microsoft is working with Google to bring a native ARM64 version of Chrome to Windows 10 on ARM and as Mozilla announced today, it, too, is working on bringing a native version of Firefox to Windows 10 on ARM. The organization is doing so in cooperation with Qualcomm.
Typically, to make any Windows 10 application run on ARM-based machines, Microsoft uses a number of emulation techniques. Those work quite well, but they do incur both power and performance cost. Native applications obviously don’t need emulation, so they run faster and more efficiently.