Abysmal Performance in Fusion 12 after upgrade to macOS Big Sur

[WTell]

After upgrading to macOS Big Sur, performance on my VMs went from great to utterly abysmal. Remedial tasks like opening the Start menu, opening Notepad etc. can now take up to half a minute. Windows are drawn on the screen line-by-line with half second intervals.

The host computer is a 2018 Mac mini with ample memory, disk and CPU. The issue was not present under Fusion 12.0.0 before upgrading to macOS Big Sur. Toggling "Disable Side Channel Mitigations" has no effect.

The attached screenshot shows the vmx processes of three VMs after the VMs have been idling overnight, with no applications open. The VMs (running Windows 10) are pegging the CPU while doing nothing.

[ColoradoMarmot]

Nope, not responding to you, sorry.  Regressions like this are frustrating - hopefully Apple will fix it in their hypervisor framework in 11.1.

[nobody456]

> hopefully Apple will fix it in their hypervisor framework in 11.1

I remain amazed that they went for that framework in the first place, given their overall long term trajectory in terms of x86...

[nobody456]

Good news – Fusion 12.1.0 just arrived, and it does fix the performance problem for me, i.e. with "side channel mitigations" re-enabled, it seems as fast as it was before the Catalina to Big Sur update earlier this week. Yay, thanks VMware!

https://docs.vmware.com/en/VMware-Fusion/12.1.0/rn/VMware-Fusion-1210-Release-Notes.html

• Performance improvements, bug fixes and security updates
• Nested virtualization is not supported without VMCS shadowing

[mlippold1]

@nobody456  Could you tell us a bit about your virtual machine and Mac hardware specs?

Are you doing VBS (Virtualization Based Security) with a TPM or just a VM within that VM or something?  I'd rather not go through the pain of updating to Big Sur again and then having to back off to Catalina.

[nobody456]

> Could you tell us a bit about your virtual machine and Mac hardware specs?

sure – spring 2020 MBA (4C/8T Icelake, 16G, 2T), BS 11.0.1, Fusion 12.1.0 + W2K SP4 VM (installed as 2C, usually run as 1C, VM HW v18)

> Are you doing VBS (Virtualization Based Security) with a TPM or just a VM within that VM or something?

no TPM, no nesting – just a simple VM

[m0leX]

yeah, that's crazy

[mlippold1]

Ok thanks, sounds like this isn't going to affect the problem I have.

[WTell]

As a general update: The issue has not been resolved with the 12.1.0 (17195230) update. The issue remains present when "Core isolation" is enabled in Windows while "Enable hypervisor applications in this virtual machine" is turned on.

[laurin21]

The issue is still there on my machine today....

[mlippold1]

While I can't confirm this is still a problem, because I immediately went back to Catalina, I've heard nothing that leads me to believe that others have had their problem fixed.   VMWare hasn't even acknowledged this as a problem as far as I've seen.   VMware, this *is* a problem.   Please address it.

[vandaveer]

Well... I spoke too soon. This week my performance issues returned with no changes to either the host or guest machines. My VM has returned to be completely unusable. Very minor CPU usage on the Big Sur Mac Mini but CPU completely used up inside the VM. I misspoke before when I said that I was using compat 16. My machine that is behaving is 16 and the one that is unusable is 18. I have client side mitigations turned off but hypervisor turned on in the machine for Docker dev.

[mysticole928]

I read that VMware fixed the nested VM performance issue.  It did not.

As soon as I use WSL2 (in the Windows Terminal, part of VS Code, or as a stand-alone program), the performance is so poor that Windows is unusable.

[mlippold1]

Agreed, but you'd think there was no problem judging by the stunning lack of VMWare acknowledgment.

[mysticole928]

I really don't understand the radio silence at all.

I use Fusion with a second external monitor and, often, it can't paint the screen correctly when minimizing or maximizing the screen.  I don't know if it's the Mac or Fusion or both.  

How does such software get sold?  

Better yet, I know that companies don't have feelings because they're not people however, why don't people at VMware care?

[JasonSimpson]

Reverting my VM to Hardware 16 resolve the main performance issues for me (I could see the screen repainting with Hardware 18 and Hardware 17 -- it went back to snappy/instant with Hardware 16).

[laurin21]

Thanks Jason, that actually helped with my VW as well! It is not back to 100% of its former performance but it's close 😄

[mlippold1]

@laurin21 @JasonSimpson Are either of you running Win 10 VMs with virtual TPMs/Bitlocker/Credential Guard etc. under Big Sur?   Just trying to get an idea on whether or not this would solve my issues as well (if I take the plunge back to Big Sur).

[JasonSimpson]

I am not running any of those, to my knowledge. Sorry, not the most sophisticated VM user. Just needed windows environments in order to have different versions of Microsoft office. 

That said, my windows 7/office 2010 machine never felt slower, even with less resources thrown at it (I have an 8-core i9 iMac, 64 gig ram, SSD drive). Only my win10/office 365 machine got slow.  I typically run them both at the same time, full screen, on different monitors (4K and 5k). Hope the additional info helps. 

[mlippold1]

@JasonSimpsonOk, thanks.  I'll hold off on going back to Big Sur, I believe my issue is related to nested VM activity which it doesn't sound like your issue involved.

[lnaie]

Guys,

I can confirm that turning OFF the feature "Enable hypervisor applications" in the VMware Fusion makes the Win10 VM run smoother. Actually as it should be.

But that means there won't be any support to run Docker Desktop in the Win10 VM. So you'll have to use the Docker desktop installed on your host OS. After all, who wants to run a VM inside a VM on a macbook pro 16" i9 maxed out? 😄

PS

The heating problem of macbook 16" gets under control, after this change. 

Btw, I bought this dev rig with the idea to be able to use dev tools and sdks across all spectrum. Mainly I use Visual Studio and .not core, docker, xamarin, but a lot of linux based tools as well etc. i9 throttling because of the chassis heating is the issues here and I look forward to the future when M1 is going to support Win10 VMs. Will switch over right away. 🙂