During review of https://github.com/openjdk/jdk/pull/12290 we observed that `startsWith` does not optimize as well as `equals`, due a lack of intrinsic support. An experiment there showed that special-casing `startsWith` to delegate to `equals` if the lengths matches is a speed-up, but perhaps it can be adapted to use `Arrays.mismatch`/`ArraysSupport.vectorizedMismatch` directly with a speed-up for all cases.

Investigating other methods in String, like compare, might see similar opportunities.