I'm filing the following bit of bug 4097023 as a separate defect,
because it's the only part of that bug that does not require an
API change....

Locale.equals is called in many places. It can be sped up by
using String.intern on all of the fields of the Locale in
all construction. Then equals becomes:
        if (language != other.language) return false;
... instead of using equals.