fastest way to translate large file to uppercase

From: John Leslie (johnleslie_at_madasafish.com)
Date: 01/27/05 

Date: 27 Jan 2005 03:01:22 -0800

Before I spend time testing this I wondered if anyone has any idea
what would be the fastest way to transalte all lowercase values in a
file to uppercase :

tr or awk or maybe sed?