Even on a 64-bit system, you can make AutoCAD 2012 even "better" by following these expert performance tips from AUGI Forums :
Keep the Properties and Layer palettes closed when not actively in use to free up system resources. System requirements for AutoCAD 2012 - Autodesk
Windows 7 is widely considered more efficient at multi-tasking for older software than modern OS environments, which can sometimes struggle with legacy CAD drivers. Benefits of a Portable Version
Keeping the command line docked rather than floating saves GPU processing power.
It allows you to run AutoCAD 2012 alongside newer versions of the software without version conflicts. System Requirements for Peak Performance
Turning off this feature can significantly reduce lag during drawing.
Running a portable version of on Windows 7 64-bit offers distinct advantages for legacy projects, hardware with limited resources, and users who prioritize speed over modern bloat. Why AutoCAD 2012 on Windows 7 64-bit is "Better"
According to JTB World , AutoCAD 2012 was specifically noted for having faster startups when running on Windows 7 compared to previous versions.
For many professionals, the combination of 2012-era software and Windows 7 remains a "gold standard" for stability and performance: