I have a Delphi 2009 program that handles a lot of data and needs to be as fast as possible and not use too much memory.
What small simple changes have you made to your Delphi code that had the biggest impact on the performance of you program by noticeably reducing execution time or memory use?
Thanks everyone for all your answers. Many great tips.
For completeness, I'll post a few important articles on Delphi optimization that I found.
Before you start optimizing Delphi code at About.com
Speed and Size: Top 10 Tricks also at About.com
Code Optimization Fundamentals and Delphi Optimization Guidelines at High Performance Delphi, relating to Delphi 7 but still very pertinent.