Let me present another reason for minifying that this thread doesn't seem to present. In React's codebase, we spread around lots of helpful warnings (those warnings are one of React's less spoken niceties), which goes through a processing step where `if (thisIsDev) {expensiveCheckThenWarn()}` turns into `if (false) {expensiveCheckThenWarn()}` for prod, and then the minifier guarantees to strip it out completely. For example, all the `propTypes` runtime type checking is gone in prod. Those were expensive.

For React-Native for example, I've heard people going from 15fps animation to 60fps when going into prod (!). I always tell them to benchmark their animation on the prod build, because dev build is _not_ representative of the perf you get.

Granted, it doesn't necessarily need to be the minifier's job. But that's the way things are currently done in JS.

If the minifier provides that much more incentive for helpful error messages then I'm all for it. It has helped us avoid a huge amount of duplicate questions when people start with React too. As a matter of fact, I think most libraries should adopt this approach for this feature alone (Webpack makes this process less of a hassle, but we can do better). Otherwise you'd be caught between inserting expensive checks and not inserting them out of perf concern, which would be a true premature optimization.