site:developer.chrome.com/docs/web platform/optimize inp actionable recommendations exact quotes optimize INP input delay event callbacks rendering delay

The requested

developer.chrome.com/docs/web-platform/optimize-inp

INP components

• Input delay: “starts when the user initiates an interaction with the page, and ends when the event callbacks for the interaction begin to run.”
• Processing duration: “consists of the time it takes for event callbacks to run to completion.”
• Presentation delay: The available evidence confirms this as the third component, but does not contain its complete definition; interactions consist of “the input delay, the processing duration, and the presentation delay.”

Actionable recommendations

• Keep every component of an interaction “as short as possible” rather than optimizing input delay alone.
• For high input delay, investigate other work occupying the main thread before the interaction’s callbacks can begin; the interaction itself “may not have been the direct cause of slow INP.”
• For high processing duration, reduce or defer work performed by event handlers because “the interaction event handlers was the direct cause of the slow INP.”
• Audit first-party, framework, library, and third-party listeners: “Any code running in any event listener will delay the interaction.”
• For high presentation delay, investigate browser rendering work after callbacks, but the supplied snippet truncates Chrome’s exact recommendation.

Insufficient evidence is available to quote the complete presentation-delay definition or its full remediation guidance exactly.