Steve Souders of Yahoo explains how to make web pages faster by front-end optimizations. About 80% of the user perceived response time is due to front-end rather than back-end. Plus front-end optimization may be easier than backend optimizations. If you haven't hear of the technique of CSS sprites, you might consider using it since it reduces the number of HTTP requests (one of the primary rules for making web pages faster).

Steve Sounders is author of the book High Performance Web Sites: Essential Knowledge for Front-End Engineers