I don't really think that a comparison to Rust is all that useful. Rust and Pony are really intended for different purposes. Rust is systems programming language. Pony is an application programming language that provides an actor model for concurrent programming and a runtime to support the actors and perform garbage collection.

A valid comparison would be to compare a Pony program to specific type of Rust program that involves considerable concurrent processing of data.

Pony's killer feature is a type system that allows programs to be written that are guaranteed to be safe from concurrency bugs. Like Rust, the Pony compiler is based on LLVM, and Pony programs compile to native code. Due to the Pony type system, the Pony GC is very efficient. Pony performance is pretty good, but as a language Pony is about much more than performance.