I've upgraded VirtualBox to v5.2 and all my VMs are running extremely slow (operations that were taking seconds are taking minutes now). I've tried Windows 7 and Ubuntu guests so far with the same results. The host OS is Windows 7 x64, virtual machine files are on a SSD drive. It seems that performance is restricted by disk operations (host's disk indicator glows all the time).
Any ideas how to fix it?

  • How much free space is left on the SSD? If less than 25% then the SSD may simply choking.
    – LPChip
    Nov 11, 2017 at 22:03
  • 1
    @LPChip, SSD is fine, I checked it.
    – user626528
    Nov 11, 2017 at 22:11

3 Answers 3


In some cases, reinstalling the guest additions might help in these sort of situations

I have had to do this on some VMs after upgrading. No idea of the underlying causes, but it seemed to fix my issues (which did include slow performance.)

  • This might be a good idea, but it is a comment with a request for clarification and not an answer. Nov 11, 2017 at 23:48
  • I did reinstall guest additions, and no, this didn't solve the problem.
    – user626528
    Nov 11, 2017 at 23:50
  • ehh. Possible fix, and it seems a bit better to me after some rewording.
    – Journeyman Geek
    Nov 12, 2017 at 6:24
  • Yup, Guest Additions totally fixed it for me. I must be tired.
    – CAD bloke
    May 13, 2018 at 8:27
  • Switched from Virtual Box 5.x to a newer 6.0.22 version, and saw a large decrease in my Windows 10 VM performance (e.g. application freezes, slow context switching, etc.), to the point it was very frustrating to use. Re-installing the latest Guest Additions seemed to clear up the issue! Much appreciated!
    – Kevin
    Jun 23, 2020 at 2:25

The solution that worked for me: delete the SSD drive (where the VM files reside) via the Device Manager, reboot, refresh devices and reinstall SSD drivers, reboot.


I have a virtual mac running on a PC and solved this problem, for me anyway:

  1. I went into the settings for the virtual machine
  2. Selected "network"
  3. Switched from "NAT" to "bridged adapter" This made the "Name:" field active.
  4. I changed the "Name" to "Broadcom 802.11ac Network Adapter", because that's what the PC is using right now.

Now, the virtual machine is as fast as the PC for networking

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