That makes sense. Performance predictability and ease of diagnosing performance issues are also known issues as discussed in this post about Swift 6 design priorities: Design Priorities for the Swift 6 Language Mode
I've certainly found myself having to look at disassembly to determine what the optimizer did with my code more often than I would personally hope for, which is why work like @Michael_Gottesman is doing on optimization remarks/"assembly vision" is so exciting: PSA: Compiler optimisation remarks - #5 by Michael_Gottesman