Investigating usage of minitrace instead of tokio-tracing
Recently a library just made the show on r/rust, called `minitrace`: https://reddit.com/r/rust/comments/1abbyc9/announcing_minitrace_06_a_modern_alternative_of/
https://github.com/tikv/minitrace-rust
https://crates.io/crates/minitrace

It is marketed as extremely fast and provide the following benchmark: 
https://github.com/tikv/minitrace-rust/blob/master/etc/img/benchmark-arch.svg

The sensible difference with tokio-tracing is that there are no Span level, only a global level. But in the way that we use tracing it shouldn't change something. It is not a drop-in-replacement.