QEMU is a generic and open source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OSes and programs made for one machine architecture on a different machine architecture. This is different than VMware, VirtualBox, or Hyper-V where you’re running different operating systems on the same architecture.

The x86 platform is not optimized for real-time usage. Real-time behavior of a system depends a lot on low latency interrupt handling.