Interaction to Next Paint (INP) is a new Core Web Vital metric focused on responsiveness that is scheduled to replace First Input Delay on March 4, 2023. Optimizing for INP is easier with the right tools to monitor and track it.
What Is Interaction to Next Paint (INP)?
INP measures the amount of time a site visitor waits after doing something like clicking a button or typing and the time it takes for the website to provide a visual feedback. INP is a metric showing the amount of time visual feedback is blocked after a user interaction.
The idea behind this metric is that an unresponsive webpage is a poor user experience. For example, adding a product into a shopping cart should immediately produce a visual feedback response showing the site visitor that the interaction was responded to. In that specific example, INP is not measuring the time it takes to add a product to the shopping cart, it only measures how long the visual feedback of that action is blocked.
Lower INP scores mean fast response times, which is the goal. Good INP scores are those under 200 milliseconds.
JavaScript and CSS are the primary targets to look at for INP optimization.
INP measures the following user interactions:
- Mouse clicks
- Taps on devices that have a touchscreen.
- Pressing on a keyboard (both physical and virtual keyboards)
INP Measurement And Optimization Tools
There is no tool that can singlehandedly fix INP problems because the problems originate in the JavaScript and CSS used by themes, plugins, features and extra functionalities used on a webpage.
For example, installing and using an image carousel or animation effects will load extra JavaScript and CSS code which can negatively impact INP scores. Minifying JavaScript and CSS isn’t always the solution, which means a key step for optimizing for Interaction To Next Paint is to audit the code and identify anything that doesn’t help the webpage and the user achieve their purpose.
Thus, the key functionality of an INP optimization tool is to identify what’s blocking or delaying the visual feedback from a user interaction.