Unsolvable and annoying VirtualBox slowdown

Since end of December 2016, I was using my personal computer to work from home. All my development environment was living in a VirtualBox CentOS virtual machine. That was working very nicely until March 13th. All of a sudden, the virtual machine became annoying slow. Starting the virtual machine took twice the time as before and everything was taking several seconds to start. It became impossible to start Thunderbird and connect to my corporate email through IMAP.

I tried to restart the virtual machine, reinstall VirtualBox, fiddle with the parameters of the virtual machine, nothing worked! The only workaround that helped a bit and at least allowed me to work was to increase the number of virtual CPUs from 2 to 4. However, even with that, when I was switching windows with Alt-Tab, it was taking several seconds for the window selector to pop up. Typing on the terminal was sluggish, sometimes as if I was connected through SSH on a slow server! But my machine was running locally! Running the unit tests of the main component I was developing used to take 4 minutes and a half on that machine. This bumped to more than 5 minutes, and even 6 minutes last week.

None of the suggestions on forums and nothing I thought about could solve this. I set the power plan to maximum performance so the CPU wasn’t throttled down. I fiddled with virtualization and paravirtualization options, disabled 3D acceleration, enabled it again, absolutely no change. Even the GRUB menu was taking a few seconds to display rather than appearing instantly as before. Maybe this is a CPU issue? I checked the CPU temperature using Speccy: everything seemed normal. VirtualBox was the mainly affected program, the rest was working fine.

This really seemed like a nasty Windows 10 update that screwed everything up. I could attempt a system restore or I could recover the last CloneZilla image I had, but if that was a Windows 10 update, the update would reinstall and thinks would screw up again. I would thus need to downgrade to Windows 7.

The issue persisted more than a month. Sometimes, I tried stuff without success: recreating the virtual machine, copying the VDI files somewhere and putting them back on my SSD (in case of filesystem corruption), checking my NVIDIA settings because the slowdown was mainly affected GUI rendering, etc.

The day before the first slowdown, two things happened: I ran CCleaner and Avast got updated. I tried to restore the registry backup CCleaner made before it cleaned registry: that failed once again. Windows couldn’t restore the registry backup. I tried to disable Avast temporarily: no effect. The hypothesis of a flaky Windows update was the main one, but no update were coming to fix it. Maybe they won’t fix it, because they offer Hyper-V, and they would love people switching from VirtualBox to Hyper-V. But that would involve reinstalling CentOS on a new virtual machine and recreating all my development environment. I could try VMWare Player instead, I think it can migrate a VirtualBox machine, but nothing told me it wouldn’t be affected as well by this issue.

Monday morning, April 17th, I tried all what I could to fix this. I was ready to attempt the system restore if needed. However, it was too late for a simple restore through Windows: I would need to use my CloneZilla image and take the risk Dropbox wouldn’t be smart enough to detect there is an old directory to update and not replace the contents in the cloud with the restored old directory. In case Dropbox screwed up, I backed up my Dropbox folder. I also backed up my virtual machines that I would need to restore after the Clonezilla recovery.

Before doing that, I tried to uninstall CCleaner: no success. I tried to remove NVIDIA Experience: no success. Two days ago, I removed the 3D vision drivers without effect. Then I removed Avast. At this point, I had little hope. I was ready to plug in the external hard drive with the Windows 10 image on it. But before, I rebooted, tried the virtual machine one more time and then, finally, it worked! It wasn’t slow anymore!

I pushed as far as starting my Ubuntu virtual machine and upgrading it from 16.10 to 17.04. This went well, without any issue. I’m writing this post from Ubuntu 17.04, running inside my VirtualBox environment which is finally fixed.

It is not the first time VirtualBox is hindered by an anti-virus program. It happened at work with Symantec Endpoint Connection. I had to downgrade to an old VirtualBox for a few releases until that finally got fixed. VirtualBox or Avast will have to fix something for this system to work again. For now, I am using the anti-virus built into Windows 10. I don’t know if I will retry Avast, reinstall AVG or finally give up and pay for Symantec’s Anti-virus or Kaspersky.