Click. Wait. Wait. Wait. Leave.
That is the user experience on most websites.
Someone taps your menu button. Nothing happens for 300 milliseconds. Then 500. Then they are gone.
That delay is FID. And Google is watching.
What FID Actually Measures
First Input Delay captures the time between a user's first interaction (click, tap, key press) and when the browser actually responds. It is one of the three Core Web Vitals that Google uses as a ranking signal.
It is not measuring how long the action takes to complete. It is measuring how long the browser is too busy to even start processing it.
Under 100ms is good. Over 300ms is a problem. If your LCP is also bad, start there first — we have a full guide on fixing LCP.
Why Your FID Is Bad
One word: JavaScript.
Your page is loading. The browser is busy parsing and executing a mountain of JavaScript. A user clicks something. The browser says, "Hold on, I am busy."
That "hold on" is your FID score.
Quick Wins
Break up long JavaScript tasks. Defer non-critical JS. Remove third-party scripts you do not actually need. (Do you really need that live chat widget, that heatmap tool, and three analytics scripts?) If your site is built on a JavaScript framework, check our JavaScript SEO framework comparison — some frameworks make this harder than others.
rolls eyes
Use web workers for heavy computation. Lazy-load what you can.
And for the love of rankings, track your progress. 113 tasks. Free. 30 seconds.