I still don't get that. Regardless of the vectors you pass to c_move, c_move will attempt to move the entity exactly that distance. There is absolutely no dependence on the framerate. If you pass a vector of length 10 to it it will return 10 - if there is no obstacle.

That means: if the distance covered is framerate dependent you already gave c_move a frame rate dependent speed vector. And that's what you'd want to do in most cases anyways.