There's a big difference between running native ARM software on ARM and emulating x86 to run Windows. If this Mac was x86, it could have probably run Windows much faster thanks to virtualization
On Apple silicon, Parallels can’t run x64 windows, it is using the ARM version of Windows. The x64 emulation is provided by Windows. Of course this is inefficient, but not everything is automatically 2x slower: any OS code you invoke is not running as x64 emulation, and IO and memory access is not penalized by the emulation (but certainly somewhat from virtualization). I was pleasantly surprised how fast you can run x64 windows apps.
Yeah I wasn't aware that Microsoft allowed that nowadays. Still, it's not ideal anyway, because in my experience Windows apps that are compatible with ARM are 90% either FOSS or portable on other platforms anyway. You use Windows to use x86 apps; if you don't need x86 apps you are generally better not using Windows at all, and if you need them they'll probably run poorly on ARM due to multiple layers of emulation. Wine is still an option, though. They support Rosetta on Mac and FEX/Box64 on Linux, so they may lead to better performance than Parallels
> I was pleasantly surprised how fast you can run x64 windows apps
In general as long as you have a fast enough machine emulation isn't that bad. Apple was doing that already for 68k with PPC and most people didn't noticed due to how massively faster their first PPC computers were. Still, the issue is that here we're not really talking about a high-end CPU aren't we
