Increased accuracy for Visually complete and Speed index—measurements may be impacted

This is an announcement for the OneAgent version 1.171 release: you may see a change in Visually complete and Speed index calculation once you upgrade to OneAgent version 1.171.

Improved calculations reflect above-the-fold experience more precisely

The Visually complete metric measures the time it takes for the visible portion of a web application to fully render on your end-users’ device screens. Analyzing the Visually complete user-experience metric helps you understand what can be done to improve your application end users’ above-the-fold experience.

Web applications can be built in a number of different ways. As we’ve learned more about how our customers’ web applications work, we’ve had the opportunity to improve how we calculate our Visually complete and Speed index metrics, which DOM elements we include, and how much influence the DOM elements have on these values.

Visually complete as key performance metric

Changes

We’ve made a few changes to Visually complete and Speed index calculation to reflect even more precisely what the end user perceives.

  • Speed index calculation now takes more elements into account. Earlier, either the slowest images or the slowest mutations were used for calculation, now both are used.
  • Calculation of the visible area of an element is now more accurate when an element is partially outside the visible area—this change impacts both Speed index and Visually complete.
  • The visibility of elements is now detected in more ways, so invisible elements have no impact on Speed index and Visually complete calculations.

Implications

Because of these changes, the values for Speed index and Visually complete measurements may drop, depending on how your application is implemented. Your measurement values may drop if your application has:

  • Elements with {{ opacity: 0 }}.
  • Elements outside the visible area that are otherwise visible (for example, {{ display: block }}).
  • Visible images and DOM manipulation occurring during page load.

The above changes will be implemented in OneAgent version 1.171.

You can find more information in our Visually complete and Speed index help.

Stay updated