Snail execution mode is active

[Richard889]

Hello virtualbox community.

I am getting this warning in my VBox.log "Snail execution mode is active" and my virtualbox linux guest OS is running very slow. I have attached the full VBox.log file with this post

Code: Select all

00:00:04.757641 NEM: Adjusting APIC configuration from X2APIC to APIC max mode.  X2APIC is not supported by the WinHvPlatform API!
00:00:04.757644 NEM: Disable Hyper-V if you need X2APIC for your guests!
00:00:04.757660 PGM: Enabling NEM mode
00:00:04.757880 NEM:
00:00:04.757880 NEM: NEMR3Init: Snail execution mode is active!
00:00:04.757880 NEM: Note! VirtualBox is not able to run at its full potential in this execution mode.
00:00:04.757880 NEM:       To see VirtualBox run at max speed you need to disable all Windows features
00:00:04.757880 NEM:       making use of Hyper-V.  That is a moving target, so google how and carefully
00:00:04.757880 NEM:       consider the consequences of disabling these features.
00:00:04.757880 NEM:
00:00:04.757945 CPUM: No hardware-virtualization capability detected
00:00:04.757949 CPUM: fXStateHostMask=0x7; initial: 0x7; host XCR0=0x7
00:00:04.761848 CPUM: Matched host CPU INTEL 0x6/0xaa/0x4 Intel_Atom_Unknown with CPU DB entry 'Intel Pentium N3530 2.16GHz' (INTEL 0x6/0x37/0x8 Intel_Atom_Silvermont)

I searched for that warning and did everything I could to disable windows hyper-v but I still cannot get that "Snail execution mode is active" to go away and my VM is still running very slow.

The host operating system is Windows 11 running on a laptop "HP ZBook Firefly".

• I made sure to turn off all features on windows related to hyper-v.
• I made sure to turn off "Memory Integrity" which could interfere with virtualbox.
• In the windows task manager Performance and CPU window, I can see "Virtualization Enabled"
• I've allocated enough memory, video memory and CPU cores to my VM.

Screenshot 2025-08-02 113415.png (70.5 KiB) Viewed 3944 times

Screenshot 2025-08-02 114213.png (81.12 KiB) Viewed 3944 times

[orev]

Try running the DG Readiness tool (https://www.microsoft.com/en-us/downloa ... x?id=53337) in disable mode. That's the only thing that worked for me.

[Byroniac]

Have you disabled Core Isolation Memory Integrity in Microsoft Defender, if you are on Windows 10 or 11? That is an additional step required on my machines. I do not know about BitLocker, but something like that might also cause the issue. Hope this helps.

[sixeyes]

Try running the DG Readiness tool (https://www.microsoft.com/en-us/downloa ... x?id=53337) in disable mode. That's the only thing that worked for me.

Thank you so much for sharing. This was the final piece I needed. I'd turned off all the Hyper V stuff in Windows features, disabled the memory integrity bit but still wasn't working.

A bit scary seeing the boot level prompts but pressing the Windows key to disable both DG & CG got my VM back to normal.