Because practice is not the same as theory. It's both faster and slower than C, depending on the program, but overall slower. The answer to why is deeply comple

Because practice is not the same as theory. It's both faster and slower than C, depending on the program, but overall slower. The answer to why is deeply complex and varies on a case-by-case basis. Rust is far more complex than C, so some language features compile down to a LOT more IR (intermediate representation) than C, and LLVM is left to try and make the best of it. Many problems in compilers are NP-complete, and the compiler will use heuristics and other techniques to get an approximately good enough answer. Like register allocation. The more complex the starting state, the less well that tends to work out. But there's other things too, Rust has bounds checks for example, while C often does not. C has null-terminated strings, while Rust strings store a length. Rust doesn't have aliasing, but doesn't yet (last I checked anyway) optimize for that. It will one day though. This is just touching on an extremely nuanced and complex subject. But C is typically faster than Rust, and will likely stay that way.