Performance Budget
Defined limits on website performance metrics that must be maintained.
Definition
A performance budget sets explicit limits on performance metrics—page weight, load time, time to interactive—that teams must stay within. Budgets make performance requirements concrete rather than aspirational, providing clear targets that guide development decisions.
Effective budgets are enforced through automated testing that catches budget violations before deployment, preventing performance degradation from accumulating unnoticed.
Why It Matters
Without performance budgets, websites gradually slow as features are added without performance consideration. Budgets force tradeoff conversations and maintain performance as a development priority.
Performance directly impacts user experience, SEO rankings, and conversion rates, making budgets a business investment rather than just technical preference.
Examples in Practice
A performance budget required teams to offset any JavaScript additions with equivalent removals, preventing the steady growth that had slowed their previous site.
Budget enforcement caught a marketing tag addition that would have added 2 seconds to load time, prompting optimization before deployment rather than after user complaints.
Teams competing for limited page weight budget produced creative solutions that delivered features with minimal performance impact.