TL;DR:

For a typical image rich, latency–bound page using a high–speed, low–latency connection, visual completion was achieved 5% faster on average.

For an extremely image–heavy, bandwidth–bound page using the same connection, visual completion was achieved 5–10% slower on average.

On a high–latency, low–speed connection we saw significant delays for page to reach visual completion.

...

When using HTTP/2, our bandwidth-bound pages take significantly longer to reach visual completion despite loading faster

With HTTP/2 the browser relies on the server to deliver the response data in an optimal way.

It’s not just the number of bytes, or requests per second, but the order in which bytes are delivered. Test your HTTP/2 server very carefully”

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https://99designs.com.au/tech-blog/b...mages-per-day/