Why LCP and INP Matter for Every Developer
As a developer, you might focus on writing clean code and adding cool features. But have you ever thought about how fast your website actually feels to users? That's where LCP and INP come in - two simple but important metrics that measure real user experience.
What is LCP? (Loading Speed)
LCP (Largest Contentful Paint) tracks how long it takes for the main content of your page to load. Imagine visiting a blog - LCP measures when the article title and first paragraph become visible.
A good LCP score is under 2.5 seconds. If it takes longer than 4 seconds, users will likely leave before seeing your content. The main culprits are usually large images, slow servers, or too much JavaScript blocking the page.
What is INP? (Responsiveness)
INP (Interaction to Next Paint) measures how quickly your page responds when users click or tap something. It's the delay between clicking a button and seeing something happen.
For a smooth experience, INP should be under 200 milliseconds. Above 500ms, your site will feel sluggish and unresponsive. This often happens when there are too many JavaScript tasks running at once.
Why Should You Care?
- Users leave slow sites - Over half of visitors will abandon a page that takes more than 3 seconds to load
- Google ranks faster sites higher - These metrics directly affect your search rankings
- Better user experience - Fast sites keep people engaged and happy
Easy Ways to Improve
For LCP:
- Compress and properly size images (use WebP format)
- Load important content first
- Reduce unnecessary JavaScript
For INP:
- Avoid putting too many click handlers on elements
- Show loading indicators immediately
- Break up long JavaScript tasks
How to Check Your Scores
You don't need to be an expert to measure these:
- Open Chrome DevTools (F12)
- Go to the Lighthouse tab
- Run an audit - it will show your LCP and INP scores
Start Small
You don't need to optimize everything at once. Try fixing just one issue this week - maybe compress your largest image or simplify a button click handler. Small improvements add up!
Final Thought
Building fast websites isn't just for experts. By paying attention to LCP and INP, you'll create better experiences for your users and stand out as a developer who cares about performance.
What's been your experience with website speed? Have you noticed any particularly fast or slow sites recently? Share your thoughts below!