My Ryzen 5600X is more or less fullspeed a lot of the time. But as others have said, there is currently a problem with the dynarec, and you will get severe slowdown in some places (like booting Windows) no matter what you do.

I like using guestmount. It works equally well with PCem and Qemu images and doesn't require any special permissions.

Ryzen 5 5600X
16 GB RAM
Mainly use Linux and a bit of Windows 10.

Performance is really good overall. I've played some games at fullspeed or mostly so, that I didn't expect to even be playable. Currently emulating:

Gigabyte GA-686BX
Pentium II 450
Voodoo 3 3000
Sound Blaster PCI 128
Windows 2000

Pentium II 450 is 100% most of the time on my end. There are the usual issues with emulating Windows, like for example where navigating Windows' file manager will slow down PCem's emulation. That seems to happen regardless of which CPU you emulate though.

Host CPU: Ryzen 5 5600X.