First Input Delay (FID)
FID measures the delay from when a user first interacts (click, tap) to when the browser responds. FID reflects page responsiveness. Good threshold: ≤100ms. FID is being replaced by INP (Interaction to Next Paint) since 2024.
⚡Why It Matters
Web pages must respond quickly to user interaction. Poor FID/INP is usually caused by heavy JavaScript blocking the main thread.
🔍How AiSEO Checks
AiSEO measures FID/INP via CrUX data and Lighthouse, detects long tasks blocking the main thread, and suggests code splitting and deferring non-critical JS.