mdasen has already pointed out that "2x" seems to overstate the difference by quite a bit. YARP also has a spikier max latency, which I'd expect for a GC'ed language.

I don't see a way to choose the benchmarking platform in the PowerBI dashboard, so I assume all these numbers were collected on Windows. In that case, it doesn't surprise me that YARP is faster: Envoy uses libevent for cross-platform I/O, but libevent is relatively slow on Windows. It exposes Windows-native I/O completion ports as a BSD-style socket API, and the implementation is both inherently somewhat slow and pushes buffering concerns into the Envoy code. Kestrel, YARP's underlying webserver, uses libuv instead. libuv is more actively developed (because of Node.js) and takes the opposite approach, exposing an IOCP-like API even on POSIX systems. Basically, YARP's I/O model is much closer to Windows' native model. This Envoy issue[0] is really informative if you're interested in the details.

More broadly, the .NET team that builds the Kestrel webserver and contributes to YARP and gRPC is full of performance heavyweights. I'd start by assuming that the benchmarks for their projects are thoughtfully designed. Everyone makes mistakes, but start by assuming that James Newton-King, David Fowler, and their peers are brilliant engineers leading a talented team - because they are.

I say all this as someone who doesn't particularly love Windows as a development environment, .NET as a language, or Microsoft as a company (quit after just 6 months). Credit where credit's due.

[0]: https://github.com/envoyproxy/envoy/issues/4952#issuecomment...

Edit: moogly points out that my info on the Kestrel implementation is out of date. Mea culpa!