LERX on WWII aircraft

[pandacat]

I always thought the little kink at the leading edge of wing root of P-51D is a high lift device not too dissimilar to LERX on modern jet fighters such as F-18s. However some articles I have read lately said it was none of that. And it was deleted on later H model to save weight. Also, interestingly, almost no US fighters were equipped with leading edge slats as the ones installed on 109s. I know most US fighters emphasized speed, but spring-loaded slats are not really an obstacle to attaining high speed since they are virtually retracted at high speed.