HTTP/2 & HTTP/3 — pick a scenario
0/4 donePick one and press Start, then click Next › to step through it.
Watch forThe image bar filling all the way while css and js sit at zero — then finishing last.
More about this scenario
You'll learnWhy HTTP/1.1's one-response-at-a-time connection makes a slow response stall everything queued behind it.
How it runsThe connection delivers the big image to completion before it will even start the small CSS and JS, because responses come back strictly in order.