Here is a trick I found out about from The Mad Cadder blog that speeds up the load time by disabling the digital signature validation.
- Right click on the shortcut you use to start AutoCAD, and pick the "Enable/Disable Digital Signature Icon" option.
- In the dialog box, uncheck the option.
- Restart the computer.
For AutoCAD LT
- Do a search for "AcSignOpt.exe" on your computer.
- Uncheck the option in the dialog box.
- Restart the computer