Shared publicly  - 
Google's New Speed Index Metric

Take a look at Google’s documentation on their Speed Index. What it’s measuring is how quickly the page contents are visually populated. The main difference between Speed Index and the regular old Page Speed is this:

Speed Index measures how quickly stuff appears up on the page. Page Speed measures how long everything takes to 100% load.

This is a much better way at determining how speed impacts user experience.

Brandon Fritz's profile photoPatrick Meenan's profile photoAJ Kohn's profile photoJohn Doe's profile photo
Google improvement, from the sound of it. Appear focusses on what user sees. happy
+John Mueller Is this actually a Google service or not? Because initially I also thought it was, but then noticed it's hosted on and links to a domain not owned by Google.
I don't think this is an official Google algorithm addition or even from Google.
Google does a lot of the development for WebPagetest as part of our efforts to make the web faster (WebPagetest is an open source project I started before coming over to Google).

The Speed Index is a new metric available in WebPagetest for evaluating the end-user performance (and comparing pages against each other) and it is something we developed at Google but don't go reading too much into that.

It's helpful for comparing user experiences and was developed specifically for WebPagetest.
AJ Kohn
Appreciate the comment and clarification +Patrick Meenan as well as your continuing work in this direction.
Add a comment...