---
title: "Measuring Component Performance with the Container Timing API – CSS Wizardry"
url: https://daily.dev/posts/measuring-component-performance-with-the-container-timing-api-css-wizardry-avjbixqmz
source_url: https://csswizardry.com/2026/07/meaasuring-component-performance-with-the-container-timing-api
type: article
source: "CSS Wizardry"
author: "Harry Roberts"
published: 2026-07-26T12:54:53.318Z
updated: 2026-07-27T09:00:45.025Z
tags: ["webdev"]
reading_time: 21
upvotes: 2
comments: 0
language: en
---

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# Measuring Component Performance with the Container Timing API – CSS Wizardry

**[CSS Wizardry](https://daily.dev/sources/csswizardry)** · [@csswizardry](https://daily.dev/csswizardry) · 21 min read · 2 upvotes · 0 comments

## Summary

The Container Timing API is an experimental browser API (currently in Chrome origin trial, versions 148–153) that lets developers annotate DOM regions with a `containertiming` attribute and receive PerformanceObserver entries as new contentful parts of that region paint. Unlike Element Timing, which measures a single element, Container Timing accumulates paint data across an entire component subtree, reporting `firstRenderTime`, cumulative `size`, `lastPaintedElement`, and more. Key caveats: the browser never signals when a container is 'finished', paint is not the same as interactivity, and the `size` property is not a percentage of completion. Practical use cases include ecommerce buy boxes, search result grids, dashboards, and publisher lead packages. The post covers how to set up the observer, how to collect and interpret the paint sequence, how to use `containertiming-ignore` for non-critical descendants, and how to enable the feature locally or via origin trial token. Mozilla has a positive standards position; WebKit's position is still open.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://csswizardry.com/2026/07/meaasuring-component-performance-with-the-container-timing-api>

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---

Tags: [#webdev](https://daily.dev/tags/webdev)

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