Perhaps, but: There's ongoing work exploring QUIC-in-kernel-space at https://github.com/lxin/quic https://github.com/lxin/quic, and more generally HTTP/3 will

Perhaps, but: There's ongoing work exploring QUIC-in-kernel-space at https://github.com/lxin/quic https://github.com/lxin/quic, and more generally HTTP/3 will be increasingly optimized over time as it moves towards becoming the majority of HTTP traffic (a few years off, but looks likely eventually). There's no fundamental reason I'm aware of that HTTP/3 would be _inevitably_ slower than HTTP/2, it seems likely for now that it's largely implementation details. There's plenty of internet-facing cases with average-at-best connectivity where HTTP/3 would be beneficial today, and isn't available (non-megacorp Android apps, CLI tools, IoT, desktop apps, etc). Even on the backend, it's very common to have connections between datacenters with significant latency (e.g. distributed CDN to central application server/database).