[jlawer]

bhyve (a lightweight virtualization tech) vs kvm (really kvm/qemu) isn't really a like for like fight. If your looking for something lightweight on the linux side you would go with Firecracker (AWS developed for Lambda and Fargate).

[bonzini]

Not necessarily; if a VM is properly configured userspace is out of the way as much as possible and performance is dictated almost entirely by the processor and the hypervisor, not by QEMU vs. Firecracker.