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Animation and Skewed Speed Index Results - Printable Version

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Animation and Skewed Speed Index Results - chelvan - 09-10-2016 02:18 AM

A bit confused by these results at:

https://www.webpagetest.org/result/160904_XM_29e2d224e707f29fde9963e289120990/

In looking over the filmstrip, the hero appears to display in 3.4 seconds, yet doesn't complete downloading until 7 seconds in. But I assume this has something to do with the image being progressive?
Also noticed the Speed Index is way high - 17222ms. Visually the hero appears much faster. I assume this has to do with the use of animation in the hero? In reading over the Speed Index docs it mentions this:

*******************SPEED INDEX INFO*****************************
This is the original mechanism that was used to calculate visual progress when the Speed Index was initially created and still works well but there are some cases where it has problems (video playing on pages, slideshows animating or large interstitials). It is very sensitive to the end state and calculates the progress based on the final image. It is also only measurable in a lab and relies on video capture being possible.