Performance Budgets for Real Products

Every project starts fast and then accumulates weight: one analytics script, one extra font weight, one 'temporary' polyfill. A performance budget turns 'the site feels slow' into a specific, enforceable conversation.

My default budget for a marketing surface: under 150KB of JavaScript on the critical path, one web font family with two weights, images sized and lazy-loaded by default, and a hard rule that no third-party script ships without a measured cost attached to the PR.

For product surfaces the budget shifts to interaction: input latency under 100ms, route transitions under 300ms, and no layout shift on the primary task. Those numbers map to how speed is actually felt.

The tooling matters less than the ritual. We re-run the budget check on every release candidate and treat a regression like a failing test. Speed isn't a launch task — it's a habit with a number attached.