KVM
Also called: kernel virtual machine, hardware virtualization
KVM is the Linux kernel's built-in hypervisor, giving virtual machines near-native CPU speed by using hardware virtualization extensions.
KVM (Kernel-based Virtual Machine) turns the Linux kernel into a type-1 hypervisor using CPU virtualization extensions — Intel VT-x or AMD-V. Guest code runs directly on the processor rather than being emulated, so CPU-bound work runs at close to native speed.
It is normally paired with QEMU, which supplies the emulated devices around the CPU. Proxmox, oVirt and most Linux cloud hosts are KVM underneath.
The distinction that matters when picking hardware: without virtualization extensions, QEMU falls back to TCG, which emulates instructions in software and is roughly an order of magnitude slower. On a Mac the equivalent is Apple’s Hypervisor framework (HVF); on Windows it is WSL2 or Hyper-V.
Check with grep -E 'vmx|svm' /proc/cpuinfo — empty output means no hardware
acceleration.