Scott Allen has recently posted a blog entry on the pitfalls of premature optimisation; in this specific case, optimizing LINQ queries, but the advice is timeless and technology agnostic:
“The first step in optimizing any code is to take some measurements and
make sure you really have a problem.”
It’s worth reading just for the image! (Now, if only that was Donald Knuth in the devil suit…If you’re curious, check out Knuth’s story of optimising the system idle loop…).
Donald Knuth popularised a quote which is sometime attributed to him, but is actually due to Sir Tony Hoare (probably best known for the development of Quicksort), “…premature optimization is the root of all evil.” The Fallacy of Premature Optimization by Randall Hyde is worth a look over at the ACM site.