01 A weight budget
Agree on a performance budget: KB of JS, number of third-party scripts, and an LCP target. Every new feature must pass through this filter.
02 Deferred loading
Chats, pixels, and heavy calculators — loaded after idle time or a user gesture.
03 A product decision
Ask "which metric will this feature improve?" If there's no answer, it goes into the research backlog, not into the release.
