CPU type `host` is significantly SLOWER than `x86-64-v2-AES`

[DAE51D]

I am shocked to discover what seems absolutely counter-intuitive to me, but maybe someone can explain me?

I have a stock Win11 24H2 and I initially set it up with x86-64-v2-AES and it was zipping along as one would expect.



Then I realized there is a 'host' CPU type and since I have a 128 GB 72 Core Dual Xeon (Lenovo Thinkstation P710) Proxmox server, I figured I'd just allocate directly as "native" HAS to be better/faster than emulated (anything) right? Wrong.

What I didn't expect is that the VM is barely usable!? The CPUs ALL peg at 100% and eventually settle down into the 50% range.



But you might be saying, "Well you started with one CPU type and changed it so..." And I'd say, "Fair point".

So then I created a fresh VM of Win 11 24H2 (from ISO) with "host" to start from the jump.
Same thing. UNBEARABLY slow.
I then toggled this new one to the x86-64-v2-AES and immediate speed improvement.

The only thing that maybe makes some sense to me would be that I have installed all those qemu "virt" drivers and maybe there's some magic/optimizations there?
https://pve.proxmox.com/wiki/Qemu-guest-agent


And just for S&G I RE-INSTALLED the latest qemu drivers (you know, in case there was a bug or this repaired some-mismatch conflict in the CPU now or IDK), rebooted, and still unbearably slow.
https://fedorapeople.org/groups/vir...ownloads/archive-virtio/virtio-win-0.1.266-1/


And one more sanity test, I powered down. Set back to "x86-64-v2-AES" and it's zippy fast again. ?!?!?

 

[l.leahu-vladucu]

Hello DAE51D! This sounds really weird. Just to be sure, did you read the best practices on installing Windows on Proxmox VE? These are the best practices for Windows 11. Make sure to install the correct drivers for Windows 11.

Otherwise, did you configure anything special in the CPU advanced settings? I heard about some issues if Enable NUMA is enabled.

Is there any process that consumes 100% CPU? You could try to show us a list of all processes sorted by CPU usage.


EDIT: I created a page for Windows 11, so now I'm linking to the correct wiki page for Windows 11.