QUIC is not Quick Enough over Fast Internet

Hi, I've got one. Does your team have any concrete plans to reduce the TCP vs. QUIC diff with respect to goodput [1]? The linked paper claims seeing up to a 9.8% video bitrate reduction from HTTP/2 (TCP) to HTTP/3 (QUIC). Obviously, MoQ is based on a slightly different stack, so the results don't exactly generalize. I can imagine the problems are similar, though. (I find this stuff fascinating, as I spent the last few months investigating the AF_XDP datapath for MsQuic as part of my master's thesis. I basically came to the conclusion that GSO/GRO is a better alternative and that QUIC desperately needs more hardware offloads :p) [1]: https://arxiv.org/pdf/2310.09423

A lot of the article is the same marketing spiel that Google has been using to promote QUIC (and then HTTP/3) At best those amazeballs advantages are applicable only at Google's scale, and have very little impact anywhere else. Worse, still, --- start quote --- We find that over fast Internet, the UDP+QUIC+HTTP/3 stack suffers a data rate reduction of up to 45.2% compared to the TCP+TLS+HTTP/2 counterpart. Moreover, the performance gap between QUIC and HTTP/2 grows as the underlying bandwidth increases. https://arxiv.org/abs/2310.09423 --- end quote --- And if you believe the discussion here https://news.ycombinator.com/item?id=25970258 it increased the load on the server unless you can "spend years optimizing it".

Don't have access to the published version but draft at https://arxiv.org/pdf/2310.09423 mentions ping RTT at 0.23ms. As someone frequently at 150ms+ latency for a lot of websites (and semi-frequently 300ms+ for non-geo-distributed websites), in practice with the latency QUIC is easily the best for throughput, HTTP/1.1 with a decent number of parallel connections is a not-that-distant second, and in a remote third is HTTP/2 due to head-of-line-blocking issues if/when a packet goes missing.

Curl HTTP/3 performance (https://news.ycombinator.com/item?id=39163948) shows HTTP/3 is the slowest performer compared to HTTP2 and HTTP1.1 This paper from 2017 showed QUIC performance was poor: https://arxiv.org/pdf/2310.09423.pdf With no evidence to the opposite, the article's claim that QUIC is displacing TCP for speed is dubious at best.