Code Smell 129 — Structural Optimizations

TL;DR: Don’t optimize anything until you have a real use scenario benchmark.



  1. Cover your scenarios with tests.
  2. Write readable (and possible non-performant) code.
  3. Do a real benchmark with real user data. (No, iterating your code 100,000 times might not be a real use case).
  4. If you have conclusive data, you need to improve benchmark’s found bottlenecks using Pareto principle.
  5. Attack the worst 20% problems causing 80% bad performance.


At university and online courses, we learn algorithms, data structures, and computational complexity before good design rules.

We tend to overestimate the (possible) performance problems and underestimate code readability and software lifetime.

Premature optimization often has no evidence of solving real problems.

We need to surgically improve our code when the facts tell us we have a real issue.

Sample Code


for (k = 0; k < 3 * 3; ++k) {
i = Math.floor(k / 3);
j = k % 3;
console.log(i + ' ' + j);
//This cryptic piece of code iterates a
//two dimensional array
//We don't have proofs this will be useful
//In real contexts


for (innerIterator = 0; innerIterator < 3; innerIterator++) {
for (outerIterator = 0; outerIterator < 3; outerIterator++) {
console.log(innerIterator + ' ' + outerIterator);
// This is a readable double for-loop
// 3 is a small number
// No performance issues (by now)
// We will wait for real evidence


[X] Manual

This is a semantic smell.

We might find the code is harder to read.


  • Premature Optimization


We need to stop optimizing for machines and start optimizing for humans readers and code maintainers.

We need to avoid programming languages designed for premature optimization and favor robust ones.


More Info

Premature optimization is the root of all evil is the root of evil


Photo by Priscilla Du Preez on Unsplash

Optimism is an occupational hazard of programming: feedback is the treatment.

Kent Beck




I’m a senior software engineer specialized in declarative designs. S.O.L.I.D. and agile methodologies fan.

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Maximiliano Contieri

Maximiliano Contieri

I’m a senior software engineer specialized in declarative designs. S.O.L.I.D. and agile methodologies fan.

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