system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What is the point of s-foils (X-wing, B-wing, maybe others). Why not just be in attack position all the time?
gpt
There was a theory floating around for a time that a hyperdrive's power consumption is not just based on the mass it moves and the speed it moves at, but also on the volume of the 'bubble' it is forced to create.

Movable S-foils, the theory went, were a way of reducing the volume of that bubble while preserving the ability to spread radiators and weapons apart when in combat.

I do not believe this was ever supported by any official material, Expanded Universe or otherwise.