Cap'n Proto RPC on QUIC vs. TLS/TCP

So I decided to find out whether using QUIC as a drop-in replacement to TCP for Cap'n Proto.

Turns out. It's not bad at all.

Copy-pasted the Cap'n Proto example. Also added TLS using rustls on the TCP one for a fair comparison.

How did you test it?

Start the server.

The client connects, connects to server, run for n times, then disconnect.

So, is it better than TCP?

Network	Protocl	Repetitions	Connection time	Slowest run	Fastest run	Average run	Network round trip average
Localhost	QUIC	1000	11.8ms	1.7ms	0.4ms	0.5ms	0.08ms
Localhost	TLS/TCP	1000	3.1ms	8.6ms	0.4ms	0.6ms	0.1ms
Remote	QUIC	1000	27.4ms	449.9ms	137.7ms	177.0ms	29.5ms
Remote	TLS/TCP	1000	110.0ms	788.7ms	174.6ms	211.1ms	35.7ms

So QUIC might be the way. Although, the difference is not that much. Plus, I was basically cheating on UDP connections by using 0-RTT.

It's not the best test though. The RPC run does not change at all every transaction.

My laptop (Macbook Pro M1 Pro) (client/localhost server)

• CPU: 8 power cores @ 3.2GHz and 2 efficiency cores @ 2.0GHz
• RAM: 16 GiB (probably lower)
• OS/Arch: macOS AARCH64

My VPS (remote server)

• CPU: 1 KVM core @ 2.80GHz
• RAM: 989.38 MiB
• OS/Arch: FreeBSD x86_64
• Average ping: 28.7ms

To do's:

• Copy-paste from quinn-rs and capnproto-rust examples,
• Make them somehow work together,
• Clean up the code,
• Add benchmarks (I tried),
• Turn into a fully functional plugin like h3-quinn or even tonic.