Keep the Properties and Layer palettes closed when not actively in use to free up system resources. System requirements for AutoCAD 2012 - Autodesk
Standard installations of AutoCAD can leave thousands of entries in the Windows registry. Portable versions keep the system clean. autocad 2012 portable windows 7 64 bits better
To get the "better" experience you're looking for, ensure your Windows 7 64-bit system meets these official Autodesk System Requirements : Minimum Requirement Recommended for 3D/Large Files AMD Athlon 64 or Intel Pentium 4 (with SSE2) 3.0 GHz or higher dual-core RAM 4 GB to 8 GB Disk Space 2 GB (portable versions typically need less) 6 GB for full installs Display 1024 x 768 True Color 1600 x 1050 True Color GPU Direct3D®-capable card 128 MB or greater with Pixel Shader 3.0 Tips to Improve AutoCAD 2012 Performance Keep the Properties and Layer palettes closed when
On older hardware, AutoCAD 2012 handles large 3D models with lofts and meshes more efficiently than later, heavier versions. To get the "better" experience you're looking for,
Using the 64-bit version on Windows 7 allows the software to access significantly more RAM (the recommended 4GB–8GB) than the 3GB limit of 32-bit systems, preventing crashes during complex renders.