The shift to 64-bit was less about speed and more about .

For tasks involving high-resolution rendering or large-scale architectural projects, the 64-bit architecture processes data in larger chunks, leading to a smoother user experience during complex operations. Key Features and Enhancements

To run the 64-bit version effectively, your system must meet these specific hardware and software criteria: System requirements for AutoCAD 2011 - Autodesk

Autodesk AutoCAD 2011 (64-bit): Power and Precision for Modern Design

AutoCAD 2011 introduced several tools that leveraged this increased power:

Added visual depth by allowing designers to adjust the transparency of specific layers or objects.