Poor performance of AutoCAD can be caused by several reasons:
1. Your Virtual Machine must meet AutoCAD system requirements:
For AutoCAD2009 they are:
RAM: 32-bit 1 GB (Windows XP SP2) 2 GB or greater (Windows Vista)
64-bit 2 GB
Graphics card: 1280 x 1024 32-bit color video display adapter (True Color) 128 MB or greater, OpenGL®, or Direct3D® capable workstation class graphics card.
For Windows Vista, a Direct3D capable workstation class graphics card with 128 MB or greater is required1024 x 768 VGA with True Color (minimum).
It means that you need to allocate about 1.5-2.5GB or RAM to your virtual machine to run AutoCAD and other applications well. And also set video memory to 128MB minimum.
2. If your virtual machine meets all the requirements, please check that you have the ”Dynamic Input” feature in AutoCAD disabled. Description of this feature is provided here:
Disable Dynamic input