Performance for opening and displaying a drawing can be improved by adding memory to your system, and using an OS that supports large amounts of memory. This is especially true when working on larger models.
AutoCAD-based products require at least 2 GB of physical memory (RAM) for working with 2D drawings, and 4 GB is recommended for working with 3D models.
The size and complexity of a model often defines how efficiently an application runs. If you notice increased hard drive activity, it means that physical memory has been exceeded and data is being passed to a swap file (virtual memory).
A swap file is an area on the hard drive that the operating system uses as if it were physical memory (RAM). The swap file size is basically a limit which restricts the total virtual size of the AutoCAD process. A good rule of thumb for configuring your swap file is three times the amount of physical memory on your system. This usually sets the limit high enough to prevent running out of swap space. Refer to the Help and Support information for your operating system about installed physical memory and for allocating disk space for virtual memory.
Graphics cache files are created and maintained to optimize performance and increase the regeneration speed of objects with complex geometry such as 3D solids, non-mesh surfaces, and regions. These cache files persist between drawing sessions and are saved in your . . .\AppData\Local\Autodesk\. . . folder under GraphicsCache. The maximum number of graphics cache files that are maintained is limited in number and total size by the CACHEMAXFILES and CACHEMAXTOTALSIZE system variables. If the limits are exceeded, the oldest cache files are automatically deleted.