HTTP/2 gives a lossy mobile link one TCP connection to stall instead of six

Six connections against 40 assets leaves 34 requests that cannot start until an earlier one finishes, and the busiest connection works through seven in series ^[1]. Each of those six pays its own TCP and TLS handshake first, two to three round trips before a byte of content moves ^[3].

TCP is the constraint underneath. It delivers one ordered byte sequence and knows nothing about streams, so one lost packet stalls every stream on that connection until the retransmission lands ^[5]. Six connections spread the damage: a lost packet takes out one of six, about 17% of what is in flight. One connection carries everything, so the same packet stalls all of it ^[2].

Under QUIC the streams are genuinely independent, and a lost packet delays only the file it carried ^[8]. The handshake combines transport and TLS into a single round trip, and a resumed session can put the first request inside the handshake itself at 0-RTT ^[9]. Against TCP plus TLS at two to three round trips, that saves one to two ^[3].

The measurement usually cited for this is Google's own QUIC deployment: an 8% reduction in mean search latency on desktop, a measurable improvement on mobile, and the biggest wins on the slowest connections, reported at SIGCOMM in 2017 ^[11]. Read it as a claim about Google search served from Google's edge. For the number to transfer to a Laravel app, the page would have to be bound by the same request count and loss behaviour a search response was, the traffic would have to include the slow connections where the gain concentrated, and the assets would have to be served by the host being upgraded. A Vite bundle plus a stylesheet, fonts and a dozen images is a different page shape.

There are two adoption paths in the guide. One is an nginx upgrade on Ubuntu 24.04 for HTTP/3 support, with a verification step for confirming HTTP/2 is actually negotiated ^[14]. The other is Cloudflare, which the guide says gets you HTTP/3 with zero origin changes ^[15]. With the origin untouched, QUIC terminates at the edge and the origin hop keeps whatever protocol it already spoke ^[4].

The guide bounds its own case. "On a fast office connection the three waterfalls look nearly identical. On a lossy mobile connection they look like three different websites," it says ^[17]. It also says the protocol under a Laravel app "deserves an afternoon of your time" ^[18]. The afternoon is the estimate I would check first, because the HTTP/3 half of it is a package upgrade on a live web server.