What is FID (First Input Delay)?
A metric measuring the time from when a user first interacts with a page to when the browser can respond.
Why It Matters
FID captures how responsive your page feels when users try to click or tap for the first time.
Real-World Example
A page with heavy JavaScript that takes 300ms to respond to a button click has a poor FID.
“Understanding terms like FID (First Input Delay) matters because it helps you have better conversations with developers and make smarter decisions about your software. You do not need to be technical. You just need to know enough to ask the right questions.”
Related Terms
INP (Interaction to Next Paint)
A metric measuring the overall responsiveness of a page to user interactions throughout its lifetime.
Core Web Vitals
Google's three key metrics for measuring page loading speed, interactivity, and visual stability.
LCP (Largest Contentful Paint)
A metric measuring how long it takes for the largest visible content element to finish loading.
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Related Terms
Core Web Vitals
Google's three key metrics for measuring page loading speed, interactivity, and visual stability.
LCP (Largest Contentful Paint)
A metric measuring how long it takes for the largest visible content element to finish loading.
INP (Interaction to Next Paint)
A metric measuring the overall responsiveness of a page to user interactions throughout its lifetime.
Cache
A temporary storage that keeps copies of frequently accessed data for faster retrieval
CDN
A network of servers around the world that stores copies of your content closer to users
Throttling
Slowing down requests instead of blocking them entirely when limits are approached