Living note

A Practical Performance Budget

Small, enforceable limits for JavaScript, images, and interaction latency.

A useful budget is tied to a user experience and checked continuously, not copied from an industry average.

Starter thresholds

Example mobile budget
SignalBudgetAction
Route JavaScript< 170 kB gzipBlock new dependency
LCP image< 250 kBResize or change format
INP p75< 200 msProfile the interaction