I just installed Ubuntu 13.04 (daily, full updated) and installed Windows 8 in virtualbox.

When Windows 8 is running a have huge performance issues on Ubuntu. Last week I had the same setup with Ubuntu 12.04 (full updated) and I had no problem with the overall performance.

Where is the problem and how can I fix it?


ubuntu 13.04 x64
4x3,1 Ghz Intel Sandybridge
On-board Graphics


Windows 8 x86
Graphics memory 128MB
Guest-extension is installed
3D-Acceleration active

  • What exactly is the performance drop you experience?
    – Takkat
    Apr 23, 2013 at 12:22
  • When the VBox is running many programs like dash, thunderbird, firefox, system-settings become grey for few seconds when I try to use them.
    – kmh42
    Apr 23, 2013 at 12:48
  • This is only guessing (hence no answer): try to add a second CPU to your guest VM, also try to apply an execution cap to each of them like 80%. Is VT-x enabled in both host BIOS, and the guest VM?
    – Takkat
    Apr 23, 2013 at 20:46
  • 1
    VT-x was already enabled. I switched now to 2 CPUs and I have no performance issuse till now. I will watch the situation and report later on how its peformed
    – kmh42
    Apr 24, 2013 at 7:43
  • After a few day and updates it runs pretty good. When I start the Windows 8 machine ubuntu slows down but after the start up it runs well. I think I had the performance issues because I updated and installed many software in W8 and it had 1 CPU. Now the software is installed and up to date. W8 has 2 CPUs and is starting in 5sec so there is not much of a problem now.
    – kmh42
    Apr 26, 2013 at 7:28

2 Answers 2


I believe there is a package called virtualbox-guest-utils. Install it with sudo apt-get install virtualbox-guest-utils. This should get the virtualbox drivers. NOTE: You need the latest virtualbox to support guests with recent linux kernels.


I had to do a few things:

install guest additions

install dkms (dynamic kernel module support):

sudo apt-get install dkms

add the line:


to /etc/modules.

I had already installed gcc prior, you may need that to install the guest additions. I installed the guest additions by the virtualbox menu, under devices; I didn't use apt-get.

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