Bundle size behaves like a household budget. A big clear-out feels great and changes nothing about next month.

Put it in the pull request

A size budget enforced in CI, reported as a diff on every pull request, changes the conversation from "we should look at performance sometime" to "this change costs 34KB, is it worth it?" That is a question a reviewer can answer.

• Report the gzipped delta, per entry point. Totals hide the regression that matters.
• Fail the build on the budget, but make raising the budget a normal, reviewable action. A rule people cannot change becomes a rule people disable.
• Watch dependencies with transitive weight: a date library, an icon set imported wholesale, a polyfill for a browser you dropped last year.

The most effective thing we ever did was print the delta as a comment. Nobody wanted to be the pull request that added 200KB, and no policy was needed.