Everyone thinks that the wings closing is equal to more speed, but in the movies you hear them say to open the s-foils and accelerate to attack speed.
The s-foils closing to gain more speed was a gameplay tactic used by the Rogue Squadron games, which has no real basis in actual lore.

But at the other hand, during atmosphere flight, u gain faster speeds when wings are closed, due less wind the wings take this way, cause with open wings at high speed in atmosphere, the wind can curl between the wings and make the plane very unstable

For space combat, this isn't a real problem, u have more space to strike and there is no fraction, hyperspace is another story, another space, so I think more atmosphere like conditions in this other dimension