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Performance Timing APIs

Together with industry and community leaders, the W3 Web Performance Working Group has standardized the Navigation Timing, Resource Timing, User Timing, and Performance Timeline interfaces to help you understand the real-world performance of navigating, fetching resources, and running scripts in your web application. You can use these interfaces to capture and analyze how your real-world customers are experiencing your web application, instead of relying on synthetic testing, which tests the performance of your application in an artificial environment.

The code samples and timeline charts below show the timing information for hidden iframes loaded on this page. Click on the links below to see the timing data, including a naïve method developers had to use before these interfaces were available.

Navigation Timing Resource Timing User Timing Naïve method

Code

Timeline

Metrics
Duration
Latency
Unload
Redirect
App Cache
DNS
TCP
Request
Response
Processing
Load
Latency
Unload
Redirect
App Cache
DNS
TCP
Request
Response
Processing
Load
0ms (Start of Navigation)