Posts tagged #performance

React 19.2's Activity component hides a subtree instead of unmounting it, so state, scroll position, and DOM survive the round trip. Here's how it behaves, what it does to your Effects, and where it costs you.

Next.js 16 gave cache invalidation two different functions instead of one, and the split maps to a real distinction: content that can lag versus content the user just typed.

Your field data says INP is 400ms. Your local profile says everything is fine. The Long Animation Frames API closes that gap by naming the script, the function, and the character position that stalled the frame.

Iterator helpers bring map, filter, take, and drop to any iterator without spreading into an array first. They went Baseline in 2025, and they change how you handle Maps, Sets, and generators.

Chrome ships the Soft Navigations API unflagged in 151, giving single-page apps a standardized way to measure LCP, INP, and CLS per route change instead of only on the first load.

Shadow DOM used to mean a blank page until your bundle loaded. The shadowrootmode attribute changed that, and it has been in every major browser since early 2024.

The Origin Private File System gives you byte-level, synchronous file I/O in the browser. Here's how it works, when to reach for it, and why it's the reason SQLite runs well on the web now.

A practical look at scheduler.yield(), the browser API that breaks up long tasks and keeps the main thread responsive without the setTimeout penalty.

CSS @scope reached full browser support in December 2025 — here's how to use it to write component-scoped styles without CSS Modules, BEM, or a build step.