The point is if you make sprintf locale-unaware, then your locale-independent calls like sprintf("hello %s", "world") won't be affected by all the locale-lockin

The point is if you make sprintf locale-unaware, then your locale-independent calls like sprintf("hello %s", "world") won't be affected by all the locale-locking nonsense that is causing the scaling issue. That's the "win". sprintf_l can be as slow as before if you pass in the same global locale object.