Benchmarking things like "assignment" in compiled languages is pretty meaningless. The compiler may or may not eliminate the code altogether, depending on whether it determines that it's dead code. Assignment may not even actually do anything. Even with more complicated code that definitely does something, you have to be a bit careful to make sure that the whole computation isn't deemed to be dead. It's not unlikely that Swift's current LLVM optimization passes aren't doing as much as Objective-C does, even with optimizations turned on. This won't have as much effect on benchmarks that do some actual work, even simple ones.