clouldflare CDN transmit time calculation for assets

how CDN works

[shivajikobardan]

https://www.cloudflare.com/learning/cdn/performance/#:~:text=In%20order%20improve%20page%20load,loads%20and%20lower%20bandwidth%20costs.

I am talking about this page.

It says-:

“1500ms: The five assets are delivered asynchronously to the client from the origin server in Singapore.”

1 response takes 250ms, then 5 responses should be taking 1250ms.
And

“800ms: The five assets are delivered asynchronously to the client from the edge server.”
1 response takes 50ms then 5 responses should be taking 250ms.

Can anyone explain what’s going on here? Are these values randomly picked. If randomly picked, why were they randomly picked? I think there is some math. My best bet is that the answer lies in the word “asynchronous”. But I am not sure.

[edited by: not2easy at 2:57 pm (utc) on Jun 15, 2022]
[edit reason] de-linked for readability and usability [/edit]

[not2easy]

Your bet sounds like the answer. Asynchronous means that the assets may be delivered using different resources and not loaded until they are needed (like lazy loading) so that there would not necessarily be 5 x 250ms time needed for complete availability for 5 assets. For example, that allows a page to load the first part of a page and delay loading images or scripts further down the page until they are coming into view. The concurrent loading (eager loading) can be avoided by planning your layout.

[shivajikobardan]

thanks for the answer.