How much does http/3 help for server to server traffic? Seems like larger websites can use a CDN or load balancer to do termination and then use http 1.1 to the back end. Is that good enough with large pipes and a high number of connections?
QUIC was not designed for server-to-server. In that use case, you’ll [1]likely experience poor performance due to higher CPU usage (since QUIC is a user-space protocol without TCP optimizations at the kernel/NIC level) and lower throughput.
[1]This is based on public benchmarks, try searching for `TCP vs QUIC`
The primary benefits of QUIC apply in scenarios where you have some packet loss, and are multiplexing multiple independent "transactions" (DB queries, HTTP req's, gRPC calls etc.) over a single connection.
Multiplexing is very common but unless you are at megacorp scale (or operating a cloud hosting platform) packetloss within your own wired network infrastructure isn't a super common issue. Compared to say packetloss to mobile clients on bad networks where QUIC can really provide a significantly improved experience.
