Comment by wahern

I don't understand the conflation of multiplexing and multicasting. Are we talking about the same multicasting? (https://en.wikipedia.org/wiki/IP_multicast)

Regarding QUIC CPU load, at least as of a year or two ago it's demonstrably greater then TCP+TLS. Even Google's own numbers showed higher server-side load of up to 10%, IIRC. QUIC has to do all the same work (QUIC libraries embed the same congestion control and stream management logic as TCP, even using slightly modified versions of BBR, CUBIC, etc), and then some. More over, both TCP stream management and TLS are often offloaded to the NIC, and QUIC support isn't nearly as mature there. Even with vanilla NICs, high-performance application servers use kTLS. Unless your QUIC userland stack is DMA'ing raw packets directly to and from the NIC, QUIC is doing more work.