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Pedro Rio corrspt

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@paulirish
paulirish / what-forces-layout.md
Last active December 8, 2025 09:19
What forces layout/reflow. The comprehensive list.

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics
  • elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
@paulirish
paulirish / webfont-performance-notes.md
Last active April 2, 2024 17:36
webfont performance notes

Just jotting some notes on delivering webfonts performantly…

still an incomplete draft.

Any critical fonts must be requested asap.

Critical fonts are neccessary for the above-the-fold content to be useful. Identify which of the fonts you NEED for the first render, as they get very different treatment vs the others.

You want the network reqs for your critical fonts to start ASAP. ideally the @font-face req is in a style tag, following CRP guidelines