Avoid chaining critical requests  |  Lighthouse  |  Chrome for Developers
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Avoid chaining critical requests
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Warning: This audit has moved into the Network dependency tree insight as of Lighthouse 13. For more information see What's new in Lighthouse 13.
Critical request chains
are series of dependent network requests important for page rendering.
The greater the length of the chains and the larger the download sizes,
the more significant the impact on page load performance.
Lighthouse
reports critical requests loaded with a high priority:
Note: See the
Lighthouse performance scoring post to learn
how your page's overall performance score is calculated.
How Lighthouse identifies critical request chains
Lighthouse uses network priority as a proxy for identifying render-blocking critical resources.
See Google's Chrome Resource Priorities and Scheduling
for more information about how Chrome defines these priorities.
Data on critical request chains, resource sizes,
and time spent downloading resources is extracted from the
Chrome Remote Debugging Protocol.
How to reduce the effect of critical request chains on performance
Use the critical request chains audit results to target the resources that have the biggest effect on page load first:
Minimize the number of critical resources: eliminate them, defer their download, mark them as async, and so on.
Optimize the number of critical bytes to reduce the download time (number of round trips).
Optimize the order in which the remaining critical resources are loaded: download all critical assets as early as possible to shorten the critical path length.
Learn more about optimizing your
images,
JavaScript,
CSS, and
web fonts.
Stack-specific guidance
Magento
If you are not bundling your JavaScript assets, consider using baler.
Resources
Source code for Minimize critical request depth audit
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2019-05-02 UTC.
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