I did try the most recent OVMF from QEMU 5.0 (https://git.qemu.org/?p=qemu.git;a=blob_plain;f=pc- bios/edk2-x86_64-code.fd.bz2;hb=fdd76fecdde) and there was no difference.
I will re-build qemu sometime soon. ======= $ cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 142 model name : Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz stepping : 9 microcode : 0xca cpu MHz : 659.478 cache size : 4096 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 22 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds bogomips : 5808.00 clflush size : 64 cache_alignment : 64 address sizes : 39 bits physical, 48 bits virtual power management: ======= $ grep . /sys/module/kvm_*/parameters/* /sys/module/kvm_intel/parameters/emulate_invalid_guest_state:Y /sys/module/kvm_intel/parameters/enable_apicv:N /sys/module/kvm_intel/parameters/enable_shadow_vmcs:N /sys/module/kvm_intel/parameters/enlightened_vmcs:N /sys/module/kvm_intel/parameters/ept:Y /sys/module/kvm_intel/parameters/eptad:Y /sys/module/kvm_intel/parameters/fasteoi:Y /sys/module/kvm_intel/parameters/flexpriority:Y /sys/module/kvm_intel/parameters/nested:N /sys/module/kvm_intel/parameters/ple_gap:128 /sys/module/kvm_intel/parameters/ple_window:4096 /sys/module/kvm_intel/parameters/ple_window_grow:2 /sys/module/kvm_intel/parameters/ple_window_max:4294967295 /sys/module/kvm_intel/parameters/ple_window_shrink:0 /sys/module/kvm_intel/parameters/pml:Y /sys/module/kvm_intel/parameters/preemption_timer:Y /sys/module/kvm_intel/parameters/unrestricted_guest:Y /sys/module/kvm_intel/parameters/vmentry_l1d_flush:cond /sys/module/kvm_intel/parameters/vnmi:Y /sys/module/kvm_intel/parameters/vpid:Y -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1886602 Title: Windows 10 very slow with OVMF Status in QEMU: New Bug description: 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. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1886602/+subscriptions
