What is the performance impact on Mac OS X, 10.6 specifically, with VMware Fusion or Parallels Desktop 5 for Mac when the virtual machine is not running? Stated another way, does installing Fusion or Parallels impact boot time of Mac OS X?


I've used Parallels Desktop for Mac—versions 3, 4, and 5—to access a Windows XP virtual machine once or twice a week. Given the limited amount of time that I use the virtual machine, I'm not wanting Parallels, or VMware, to impact Mac OS X's performance when the virtual machine is not running.

My suspicion with Parallels is that it does impact performance even when the virtual machine has not been activated, but I have not done enough testing to isolate the cause to confirm. I have confirmed that on startup of the Mac, there are entries in the logs related to Parallels—network adapter stuff for instance.

I reinstalled a fresh copy of Mac OS X. So far I'm happy with the boot times and performance; however, at some point I'm going to need Windows again and will have to break down and install either Parallels or VMware Fusion.

Related Research


I've never user parallels but vmware does the following even when VMs are not running:

  • Adds the virtual network interfaces on boot
  • runs a bridge daemon on at least one of the vmnet interfaces
  • Runs dhcp on the vmnet interfaces
  • Runs a nat daemon on at least one of the vmnet interfaces.

These total to about 1.5 - 2mb of ram and almost no load. So, yes, your system resources are impacted, though I doubt you'd ever notice.


There's no significant impact, its just another app with a few services associated with it. If you have a slower than desired startup time, I'd look at other apps that load at startup -- especially apps like Quicksilver and Skype.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.