What is Performance Budget?

A performance budget defines limits for metrics like page weight, load time, or Lighthouse scores. It helps teams maintain performance by setting clear, measurable targets.

Types of performance budgets

Quantity-based

• Maximum page weight (e.g., 500KB)
• Maximum JavaScript size (e.g., 200KB)
• Maximum number of requests (e.g., 50)

Timing-based

• LCP under 2.5 seconds
• TTI under 3.8 seconds
• Speed Index under 3.4 seconds

Score-based

• Lighthouse Performance ≥90
• All Core Web Vitals "Good"

Setting a performance budget

1. Benchmark current performance
2. Research competitors
3. Define meaningful thresholds
4. Get team buy-in
5. Integrate into CI/CD

Enforcing budgets

In CI/CD

• Lighthouse CI
• Size-limit
• bundlewatch

Example configuration

{
  "budgets": [{
    "resourceType": "script",
    "budget": 200
  }]
}

Benefits of performance budgets

• Prevents performance regression
• Creates shared accountability
• Informs feature decisions
• Maintains user experience

How VitalSentinel handles this

VitalSentinel is your website's revenue insurance, enforcing your performance budget without bolting on yet another CI tool. Our Synthetic Monitoring runs scheduled Lighthouse audits against your thresholds for LCP, TBT, page weight, and JavaScript size, then fires alerts via email, Slack, or webhook the moment a deploy busts your budget so you catch regressions in hours, not weeks.