This post will show how a few simple D programming constructs can turn an already fast command line tool into one that really screams, and in ways that retain the inherent simplicity of the original program. The techniques used are applicable to many programming problems, not just command line tools. This post describes how these methods work and why they are effective. A simple programming exercise is used to illustrate these optimizations. Applying the optimizations cuts the run-time by more than half.