[tinco]

A that would be hard to say. A lower limit would be reading your entire project and the dependencies that are used once, and writing the bundled/minified code once. Possibly some parts of that could be done at the same time as you determine the bounds of the dependencies as you read in the code. So O(n) where n is in operations over lines of code in your project at least.

There's probably trade-offs too. Like do you bother with tree shaking to make your end product smaller, or do you not to make your build performance closer to that optimal read-once write-once lower bound.