N10Head-of-line blocking and multiplexing

The problem

1 s on screen = 100 ms

Why does one lost packet hold up the whole page?

Six lanes, one file each

A browser loads pages of 24 files over six connections, one file each at a time. The line loses 3% of packets.

Lost packets

None1%3%5%

Live metrics for each version of the scene
Metric	HTTP/1.1	HTTP/2	HTTP/3
	—	—	—
target ≤ 400 ms	—	—	—
	—	—	—

N10Head-of-line blocking and multiplexing

One connection doing one request at a time means a slow response blocks everything behind it.