I recently installed OS X 10.10.1 inside a virtual machine using VMWare Fusion 7.1. Unfortunately, even after I installed the guest additions, the whole system was extremely laggy. Why is that? Is it so hard to virtualize OS X?
See if the VM has acceleration enabled and try disabling the eye candy stuff.
Mostly because Apple doesn't want you to do it.
Some features of VMware Tools do not work in Mac OS X 10.9 Mavericks virtual machines. These features include:
Unity
Mirrored folders
3D acceleration. SVGA only.
Drag-and-Drop / Copy-Paste of files
Multi-monitor support in full screen.
USB 3.0 support.
scratch that... from the vmware kb (for mavericks, but doubt yose is different)
i suppose that alone would make it run like a pig...
There are Yosemite-specific graphics performance issues in Fusion as of version 7.1. There's workarounds here:
http://blogs.vmware.com/teamfusion/...sues-running-os-x-yosemite-vm.html#sf35313754
Running the Beamoff app listed there makes a huge difference.
Run it natively instead of a vm. OS X is indeed rather difficult to virtualise properly. With the new graphics system it seems that El Capitan is running better in a vm albeit still a tad bit slow. Running any other OS X version in a vm requires patience, mostly due to the graphics system.