Although I use a MacBook & OSX there are several Windows programs that I can’t do without and thus have VMware Fusion running almost constantly. In the year or so that I’ve been using Fusion I’ve discovered a lot of things that can improve performance, some obvious and some not so.
This will be the post I wish I could have found when I began using Fusion 
- Get as much RAM as possible. You should have at least 1GB of RAM assigned to your VM and possibly more depending on how many programs you’re running.
- Even if you have a dual-core machine, don’t use the dual-virtual-cpu option.
- If you have the option, use a 64-bit operating system (XP 64-bit, Vista 64-bit, Windows 7 64-bit). For 64-bit VM’s Fusion will use Intel’s VT hardware extensions for virtualization which perform better for call-heavy workloads. See this post.
- Virtual SCSI drives perform better than virtual IDE drives. Note that XP discs do not come with SCSI support so you should use the “Easy Install” option in VMware which will slipstream them.
- Running a file-based Virtual Machine is much faster than a boot-camp partition. The reason seems to be that accessing to data on the NTFS boot-camp partition is slower than the HFS+ partition.
- Windows XP is faster than Vista.
- Windows 7 is faster than Vista.
- If you have the option, put your VM on an external or secondary disk. The more you can minimize access to your system disk the better.
- Some forums claim that static pre-allocated disks are faster than dynamically disks that grow as needed.. This doesn’t make much sense, other than when your dynamic disk must be resized every 2GB or so.
For reference; With VMware Fusion 2 on my 2.4GHz MacBook with 4GB RAM and running Windows 7 with no programs, Activity Monitor shows around 5-6% of CPU time being used.
2009/05/10, 23:59
Thanks for the tips. My XP box recently encountered some fatal hardware failures (never trust cheap PSUs!), so I decided to try virtualization on OSX. I’m currently evaluating VMware Fusion, but I’m still not sure if I should drop the money one it.
Concerning point two, are you giving the VM only one virtual core to keep CPU usage down on the host, or is there a performance decrease with two virtual cores?
2009/06/06, 13:01
Is the performance improvement using XP 64-bit vs XP 32-bit substantial? There seems to be some backwards compatibility issues for applications on XP 64-bit as detailed in this Microsoft article: http://www.microsoft.com/windowsxp/using/64bit/russel_exploringx64.mspx
If the performance improvement isn’t substantial, I’d rather stick with 32-bit XP for maximum versatility and flexibility.
2009/06/18, 23:19
Another reference point: Vmware Fusion 2 on my 2.4GHz Desktop with 4GB RAM running Windows XP SP3 (1.5GB alotted) with no programs, Activity Monitor shows around constant 1.5% CPU time being used.
2009/07/17, 16:03
I’m not to sure about the difference with 32/64-bit XP, but the compatibility issues would make me think twice. For Vista 64-bit though I’d say go for it!
2009/07/20, 06:52
I think Vista is too sluggish…
2009/07/29, 03:44
Do you find that VMWare is using almost no “real memory” – I have what I would consider to be a pretty normal Vista 64-bit system that is just a pig on VMWare Fusion (host is 2.8GHz Macbook Pro with 4GB RAM) – but there is almost no real memory being consumed. If my VM is only getting virtual (disk) memory, that would explain the performance hit.