Machine becomes very slow after virtualbox upgrade

[Merrilin]

I recently upgraded a virtualbox that was running a version 3.x (sorry, I did not keep the old version number). The Gentoo 32 bit guest OS was running fine until now, but became unusably slow after the upgrade.

I noticed that deactivating the settings "VT-x/AMD-V" makes the machine halfway usable (with a 3x to 4x slowdown compared to before). With that option on (with or without "nested paging"), the slowdown is definetely higher than 10 and does not allow to do much with the VM.

I have tried numerous versions of Virtualbox 4, and am currently with 4.1.8. None of those I tried did behave better.

I also tried to destroy the VM and recreate it with the same .vdi file, with no success.

[Merrilin]

I notice I forgot to mention the host OS is Mac OS X.

[Frank Mehnert]

Please attach a VBox.log file with VT-x enabled as well.

[Merrilin]

Here is a new log, obtained with the same VM with VT-x On (so that it was indeed unusably slow (I did not even try to start up an X session in the linux guest).

[Frank Mehnert]

Thanks for the new logfile. You assigned 2GB guest RAM to the guest. Could you do some more tests?

• Can you reproduce the same slowdown with 1GB guest memory?
• Does it make a difference if you enabled PAE for that VM?
• Does it make a difference if you disable nested paging for that VM (keeping VT-x enabled)?

[Merrilin]

Thanks for the update. I have just ran four tests:

-1- 1GB guest memory, PAE disabled, Nested Paging enabled

-2- 2GB guest memory, PAE enabled, Nested Paging enabled

-3- 2GB guest memory, PAE disabled, Nested Paging disabled

-4- 1GB guest memory, PAE enabled, Nested Paging disabled (the combination of all three suggestions basically).

All are in the "unusably slow" category (20x slow down roughly). I am not sure whether the logs are useful, but I attach them just in case.

[Merrilin]

I eventually decided to scrap the VM, VirtualBox version and everything, so I will unfortunately not be able to contribute any further element. The new VM (copied from the other computer actually so that I did not have to reinstall the guest at all) litteraly flies.