Me 109 pilots said the slats, when deploying made the plane very unstable because they moved out with a great speed, this was often a problem when they were about to fire while in a turning fight with an enemy plane as, while they turn behind him, they sometimes got into the slip stream from the nmy plane, the slip stream made the slats deploy unexpectedly and threw the aim off.
IMO they seem to be moving in an out a bit too much though, maybe? Even when in a quite stable turn they move in and out and it is almost hard to get by the area where they move and settle in a steady turn.