I have VirtualBox running Ubuntu as a guest environment on my Macbook Pro running Leopard OS X 10.5.

I timed the same batch of Ruby on Rails unit tests on both systems. The difference seems to be quite big.

The same suite of Ruby unit tests that take 13.4 seconds in the native OS X, take 82 seconds to run in VirtualBox Ubuntu.

Are other people doing the same kind of development noticing the same differences?

I have 4GB of RAM on the machine, and 512MB base RAM for the guest Ubuntu system (but I think this this number increases dynamically when more RAM is needed).

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    How much physical RAM is in the MBP, and how much has been alloted to the virtual machine ? That might be a place to start... – CaseyIT Apr 12 '10 at 15:27

Virtualization of an OS is always going to come at a cost. Performance of the VM is not going to be exactly like the performance of the host OS, and on top of that there's the variable of how many resources you allocated to the VM (number of CPUs, amount of memory).


My experience with Virtualbox vs other commercial hypervisors such as VMware Fusion or Parallels is that Virtualbox is usually noticeably slower.

  • Are VMWare or Parallels also noticeably slower than the native OS at tasks like running tests? – dan Apr 12 '10 at 16:21
  • In my experience, everything is slower in VirtualBox: startup, running programs, running command-line tools, ... – Frederik Apr 12 '10 at 17:59
  • VMware and/or Parallels are much better than Virtualbox. See for yourself. Both have trials. – churnd Apr 12 '10 at 20:58
  • I'm primarily interested in knowing roughly what their performance relative to the same native hardware is. 50%? Do you have a ballpark estimate? I want to know because I do have the option of just running my tests on Linux running natively. – dan Apr 12 '10 at 22:32
  • My estimates have been seat of the pants. There are too many factors for any estimate I give to be useful to your application. Best thing to do would be to test yourself. Obviously, running native is going to be faster. My latest testing with Parallels 5 has shown better Windows performance. Haven't done enough Linux testing to give any useful info. – churnd Apr 13 '10 at 2:37

Any virtualization that you can think of will come at the price of reduced performance. You can tweak settings in VirtualBox, such as increasing the amount of RAM available to the guest OS, to try to improve the performance, but there's only so much you can do. The guest OS will never run as fast as the host OS.

Considering you're virtualizing Ubuntu, have you considered using Wubi? It allows you to install Ubuntu right from Windows. It will allocate a file on your C: drive that will serve as the hard disk for Ubuntu, and it will automatically take care of setting up the dual booting. Whenever you want to get rid of it, you can uninstall it from Windows as if it were any regular application.

  • Thanks for the comment and suggestion. I don't have a Windows system. Just OS X and Linux. – dan Apr 12 '10 at 22:47

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