The EcmaScript switch spec basically says that each case statement in turn is evaluated until one becomes equal or default is encountered, so to follow the spec the basic case is equal to a bunch of if-else's.

To optimize the runtime first has to figure out that all case values are constants (and insert guards to de-opt if it doesn't hold anymore), so in essence the machinery for running this code optimized has to be very conservative (and probably why they placed arbitrary limits that really aren't suited for emulators).

https://tc39.es/ecma262/multipage/ecmascript-language-statem...