Ugh I did have a project where they dictated mqtt and it just wasn't the right tool for what they were using it for.

A) it was connecting Oculus Go and Laptop and Phone + running Unity apps + raspberry pi (running the broker + cellular board + wifi + gps + other hardware + aws)

B) they were sending 30 updates per second

C) each message originally had 50 different fields.

Parsing that 50 field json 30x a second fed the GC like no other. I ended up making them thin it down and even then I only parsed what I received 10x a second and dropped the rest to keep frame rate up (needed 60+ fps on a shitty Go).

IMO it would have been better to have used udp and a custom packet/serialization in that particular case.