Developers often optimise the code they suspect, not the code that is actually hot. A 50% gain in a function that takes 2% of the runtime is a 1% gain overall.
The fix you can use today
Profile the real workload first and find where the time and energy go.
Only work on paths that account for more than about 5% of the total.
Leave test fixtures, prototypes and code that runs a handful of times alone.
Tools that help
GreenCode Constitution skill (GreenCode researchers): open-source energy principles and a catalogue of 37 energy anti-patterns that an AI coding agent can follow to find and fix waste like this
GreenCode Constitution profiler (profile.sh) (GreenCode researchers): a script from the Constitution tooling that measures the energy of a command from processor counters, GPU sensors and an optional smart plug, and writes the result as JSON
green-languages (GreenCode researchers): a command-line tool that measures the energy of whole programs or marked sections of code, across languages
How GreenCode helps
GreenCode helps tackle this by building a load test from the system's own endpoints, recording energy as well as speed while it runs, and ranking the hotspots by the energy they use. More on this.
