* tracing is only present for logging purposes. does curl need it? It should be configurable.

* itoa is only present for performance purposes, and only seems used by the server.

* It seems that a bunch of projects in the dependency tree use pin-project which is heavyweight and instead could use pin-project-lite. Some already do, which creates both being used, so you are worse off than just with pin-project alone...

* hyper contains code for both http servers and clients. Even if the dependencies are the same (and as seen above they are not), having to compile the server code for the client means an increase in compile time. It would be cleaner to provide separate server and client flags to make it possible to turn one off.