Windows 10 very slow with OVMF

Debian Buster

Kernel 4.19.0-9-amd64
qemu-kvm 1:3.1+dfsg-8+deb10u5
ovmf 0~20181115.85588389-3+deb10u1

Machine: Thinkpad T470, i7-7500u, 20GB RAM
VM: 4 CPUs, 8GB RAM, Broadwell-noTSX CPU Model

Windows 10, under this VM, seems to be exceedingly slow with all operations. This is a clean install with very few services running. Task Manager can take 30% CPU looking at an idle system.