There is also a trick to compile your own program without optimizations, but optimize all dependencies. I too had the "Un-optimized Rust code is slow!" experie

There is also a trick to compile your own program without optimizations, but optimize all dependencies. I too had the "Un-optimized Rust code is slow!" experience when I started out, because my first project required PNG encoding and decoding, and the png crate was incredibly slow without optimizations. But it's typical for C and C++ to be un-optimized at the level of `main`, but calling into heavily-optimized system libraries like ffmpeg.