Web Performance Metrics

Understanding and optimizing key performance indicators

Time to Interactive (TTI)

Time to Interactive (TTI) is an essential metric from Google PageSpeed Insights that measures the time required for a web page to become fully interactive for the user.

Why is TTI crucial?

• Key indicator for developers
• Measures JavaScript code efficiency
• Enables optimization of critical scripts
• Reduces blocking and improves interaction fluidity

TTI performance thresholds:

Excellent (A)≤ 1.0s

Good (B)1.0s - 2.0s

Fair (C)2.0s - 3.0s

Poor (D-E) 3.0s

Core Web Vitals

Since the introduction of Core Web Vitals, Google has placed loading speed at the heart of its SEO ranking criteria.

Largest Contentful Paint (LCP)

Loading time of the largest element visible in the viewport.

Good:≤ 2.5s

Needs improvement:2.5s - 4.0s

Poor: 4.0s

Cumulative Layout Shift (CLS)

Evaluates page visual stability by measuring unexpected element movements.

Good:≤ 0.1

Needs improvement:0.1 - 0.25

Poor: 0.25

Total Blocking Time (TBT)

Measures page responsiveness by quantifying time when the main thread is blocked.

Good:≤ 200ms

Needs improvement:200ms - 600ms

Poor: 600ms

Google's algorithm and its evolution

Since the introduction of Core Web Vitals, Google has placed loading speed at the heart of its SEO ranking criteria.

💡 In practice:

A fast site improves both SEO and user experience, increasing conversions.

TTI: Key data for developers

Time to Interactive (TTI) measures the time needed for a page to become fully usable. It's a crucial indicator for evaluating JavaScript code efficiency and optimizing critical scripts.

By optimizing TTI, developers reduce blocking and improve user interaction fluidity.