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This product reached the end of support date on March 31, 2021.

Speed Index Metric

JGannon
Guide

Does Dynatrace provide a speed metric similar to Webpagetest and Lighthouse, that calculates the average time it takes the pixels above the fold to render?

11 REPLIES 11

GabrielPrioli
Dynatrace Pro
Dynatrace Pro

Hello Joe,

I'm not familiar with the calculation of the metrics by WPT and Lighthouse, but per your description the one that should be more closely related is Perceived Render Time.

The perceived render time represents how long the initial visible page takes to load.
With usual text / image size ratios the value largely depends on the loading time of the slowest image within the page's visible range.

https://community.dynatrace.com/community/display/...

JGannon
Guide

Hi Gabriel thanks for the info. In looking over the documentation it appears the timing is based on images. However, what happens if the page has no images but rather other elements such as text. The only way I think I can get this is by adding a user timing metric.

Yes, if the page has no images, the metric won't be calculated. In the doc, section Limitations: "If no images are detected within the visible screen area, no perceived render time value will be calculated."


KlausEnzenhofer
Dynatrace Pro
Dynatrace Pro

Yes it does starting AppMon 7. Read more on the capabilities here on my blog

JGannon
Guide

This is awesome for UX to have this data now available in Dynatrace

JGannon
Guide

Question - in which product is this available? I am using UEM and am new to using Dynatrace.

In all products! in UEM you will enjoy it starting with version 7. With Dynatrace RUM starting March/April and Synthetic will follow in May. early access will be available earlier eg. UEM now

JGannon
Guide

Klaus..thanks .. is there any JavaScript code that is needed to be inserted on the page to make this happen?

Just the regular Javascript agent. Nothing else is needed.

JGannon
Guide

Klaus - the timeline looks awesome. Questions.

If a W3C performance mark is inserted into a web page to measure the rendering of an element such as a hero image, data grid, etc, will those timings be displayed on this timeline. I am referencing https://www.w3.org/TR/user-timing/ and article on this here https://speedcurve.com/blog/user-timing-and-custom... - Basically I want to know when an element such as hero, or data grid actually became visible. Perhaps there is another way to do this. Until now I typically look at the filmstrip in WPT, but using the marking is more accurate.

Hi Joe,

Yes those user timing markers are being picked up but they are not impacting the visually complete metric they are kept separate and are additional markers.