The usual case for fixing a slow build is arithmetic: builds per day, times minutes per build, times engineers, times hourly cost. It is a real number and it never convinces anyone, because the number is always smaller than whatever feature is competing for the time.
The better argument is behavioural.
What a slow build changes
At thirty seconds, an engineer tries the change. At eight minutes, they think about whether the change is worth trying. That gap does not appear on any dashboard, but it is where the compounding damage lives:
- Refactors get deferred, because verifying one takes an afternoon.
- Pull requests get bigger, because nobody wants to pay the cost twice.
- Local verification gets skipped in favour of “push it and see what CI says”, which moves the feedback even further away.
By the time a team is complaining about build times, they have usually already stopped attempting the class of work that would have surfaced the real problems.
Where the time actually goes
Before optimising anything, measure. In our experience the distribution is lopsided and rarely where people guess:
- Dependency resolution on a cold cache, which is usually a CI configuration problem rather than a code problem.
- Type checking, which is often being run twice — once by the bundler and once by a separate check step.
- Image processing, which is invisible until someone commits a folder of full-resolution source assets.
That third one is worth a specific note. Source images committed at export quality are a permanent cost: every clone pays for them, every build reprocesses them, and the delivered output is usually byte-identical to what a recompressed source would have produced.
The gate that keeps it fixed
Fixing a build once is easy. Keeping it fixed needs a number that fails the pipeline. Pick a ceiling that is comfortably above today’s time, wire it into CI, and lower it when you beat it. Without that, the time creeps back one dependency at a time, and nobody notices until the team has quietly rearranged its habits around the new normal again.
