'Standard' vapor website drops 1.5% of requests, even at concurrency of 100!

The compiler is not licensed to do this transformation in general; even if we had a way to promise that the result is the same, one or both of the operators might have observable side-effects (e.g. a printing something to a log for debugging). It's interesting to think about how you would design a language that lets you tell the compiler that it can do this transformation, but Swift has no mechanism to allow it today.