I'm completely new to Macs and always used PCs so far.

Said so, I'll try to be as much specific as I can.

I just bought a MacBook Pro running Yosemite 10.10.3 and am considering installing Parallels or VirtualBox (or?) to run Clampfit (a Windows-only compatible analysis software) on my Mac. My Windows OS of choice would be XP or Windows 7 (unless otherwise suggested here).

My question is: which between Parallels and VirtualBox would be affecting the least the performance of my machine?

Please note:

  • most likely I would not need to run softwares requiring large amounts of memory together with Clampfit
  • I already have Parallels

Thank you very much for your help.



I suppose the VMWare is also an option.

However, as you know with Parallels, you can restrict the resources that are available to Window, such as the number of CPUs available between Mac and Win, the memory, and the video card memory.

Whereas a typical configuration might be to share these resources equally between Mac and Win, in your case it makes sense to reduce the resources for Win (and consequently for Clampfit), and you can fine-tune this to your liking.

I'm not certain about how much you can limit the amount of hard drive space available for Windows. I always went with the suggested 64 GB, and I don't recall if you could reduce this.


I have never owned or used Parallels so you might want to check my answer for accuracy. I am currently a VirtualBox user.

From my understanding, you can run Windows using Parallels under OS X. You can also, run the same Windows without Parallels. So you have the best of both worlds. You can run Windows with or without virtualization. This is not true for VirtualBox. Here, you would have to install a separate copy of Windows, if you do not want to use virtualization. This would require buying two Windows licenses.

  • That is incorrect on the Windows licensing. You can install a copy of Windows on up to three machines for personal use. Additionally, since you are running the "same copy" on the same machine just via a different interface, you technically only used up one license.
    – Allan
    Jun 14 '15 at 12:25
  • @Allan: I am not sure which version of Windows you are referring to. I offer this site for Windows 7. The site states the product key can be used on only one computer. Can you offer a site that says it can be used on 3 computers? I know if you have Windows 8 or 8.1 installed, you can install and activate Windows 7 without buying a license. I done this myself. Jun 14 '15 at 17:37
  • @Allan: The hardware in VirtualBox is emulated using software. Windows running in VirtualBox has no idea the physical machine is a Mac. Windows is installed to a virtual partition stored in the OS X hfs+ file system. When you install using the Boot Camp Assistant, you are installing using the physical hardware of the Mac. You also are installing to a physical partition. This is a different copy of Windows with different drivers installed. Microsoft considers the two to be separate machines. Jun 14 '15 at 18:16
  • I am basing that on Volume Licensing...it is actually 4 instances on one desktop. Anyway, the site you referenced is retail, so the number is only one. However (and this is a BIG however), you are only licensed to USE the software on one machine; you can install it on more than one. Since you cannot run Parallels and Bootcamp simultaneously - meaning one or the other, you can use the same license key for both. Ultimately, you are running Windows on the same machine. If you migrate the VM to another machine, that would be a violation of the user agreement.
    – Allan
    Jun 15 '15 at 0:28
  • Allan: I truly hope you don't take this the wrong way. Are you even aware the purchaser of a retail version is required to active Windows within 30 days of installation? Once activated on one machine, you can not activate on another machine until a certain amount of time has past or you contact Microsoft to transfer a license. At least this is currently true for Windows 8/8.1. Jun 15 '15 at 4:06

I personally like VirtualBox.

I have an iMac 27 with a 3GHz i7 cpu and 32GB RAM running Yosemite.

On a daily basis I have three VB's running: Windows 7 enterprise for Visio and MS Project, Windows 10 Tech Preview, and an Oracle Unbreakable Linux 7 server for web dev.

Everything runs great. While it obviously isn't as fast as running directly on my iMac, it is more than adequate. MySQL and HTTP response is just as fast as if I was running it on a physical machine. Windows 7 is smooth, though I have turned off most of the desktop animations (I don't like them to begin with). Win 10 is beta so it has been up and down.

However, I do have an entire Microsoft "Lab" virtualized on this machine. At any time, I can load up a private network with Active Directory, SQL Server, Exchange, SharePoint and 3 Win 7 clients. Granted, it isn't super fast, but all are responsive and work.

Now, you mentioned "analysis software" so I am guessing this is analytics. Is it CPU intensive? You can assign additional cores to the VM in VB. Does it use a GPU (from your graphics card)? You may be able to get some use out of VB but here I would suggest using a dedicated machine. The question is, how intensive is your analysis software going to be?

For the price ($0) you simply cannot beat VB. If GPU is critical, then you might have to skip doing this in a VM and opt for Bootcamp. If disk I/O is essential, either Bootcamp or Parallels.

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