Speeding up Lightroom

Has anyone located any tips on speeding up Lightroom regarding program location, library location, and file location? I'm thinking if there is anything similar to Photoshop's need for the scratch disk to be on a different drive at the beginning of the disk, etc.

Right now I have the program on one physical drive and the library and folders on another physical drive. I'm just curious if anyone has looked at moving those around.

Also, is there a performance hit having the database located on an external drive? I think Michael said on the Lightroom tutorial that the library and files were all on his external disk.