Yes, this is the "LMAX Disruptor": https://lmax-exchange.github.io/disruptor/user-guide/index.h...

You can write only-stack-alloc or limited-alloc C#, and Microsoft have put a lot of work into it (Span etc); it's just a bit unidiomatic.

Mind you, the last time I had contact with HFT it was inside an FPGA context..