Revit Performance Degraded after Upgrading Parallels, OS, Hardware

Hello,

I have a user who was running Windows XP Professional 32-bit and using Autodesk Revit Architecture 2009 with 3GB of memory allocated from a total of 5GB. The system was running fine except for instances where she would get an 'out of memory' error occasionally from Revit. In my office I have upgraded a handful of users to Vista Business 64-bit and most are running Revit 2010 64-bit so this is the first user that has come to me saying that the performance has degraded by a lot (not sure if the other users have just not voiced this themselves and are experiencing the problem as well).

Here are the specifications of the machine before the upgrade
Mac Pro 1,1
2x Dual Xeon 3.0GHz
5GB RAM (3GB allocated to VM)
Parallels 3.0
Windows XP Professional 32-bit (SP3)

Afterwards:
8GB RAM (6GB allocated to VM)
Parallels 4.0
Windows Vista Business 64-bit (with SP2 and all critical updates)

The user states that loading is slow, saving is slow, and she used to be able to have 20 windows open, but can now only have about 5. Basically everything has slowed down.

I have tried allocating 2 of 4 cores. Also, I am allocating 6144MB (~6GB) to the VM. The VM is being run from the boot camp partition. Any and all help is greatly appreciated!

 

trying 32-bit version

After requesting support from Autodesk, they have suggested that I try installing the 32-bit version of Revit 2009. Once I figure out a way to do that with the existing 64-bit version installed, I will get back here. Also, I am preparing a Windows 7 RC virtual machine for testing with Revit and AutoCAD 2010. I will also mention anything that is worth noting regarding performance over Vista.