In JDK 25, we improved the performance of the class String in such a way that the String::hashCode function is mostly constant foldable. For example, if you use Strings as keys in a static unmodifiable Map, you will likely see significant performance improvements. Example Here is a relatively advanced example where we maintain an immutable Map of native calls, its keys are the name of the method call and the values are a MethodHandle that can be used to invoke the associated system call: // Set ...