The short answer is furling a jib does affect the jib's efficiency. How much it affects it and what difference does it make is a long discussion.
When the sail is furled the leading edge of the sail becomes fatter. This disturbs the airflow across the luff and affects the sails efficiency, especially when close hauled. The further off the wind the boat sails, the less of a problem it becomes.
Which begs the questions, how much of a problem is it? If you are a highly competitive racer, it matters a lot. If you like to go day sailing or cruising, eh, not so much. Yes a furled 150% will lose some pointing ability and that will affect boat speed and VMG, however we're only talking a few degrees and a few tenths of a knot.
In some areas where there is a seasonal variation in prevailing winds, strong in spring and fall and lighter in the summer, sailors will put the smaller sail on in the windier seasons and the bigger sail in the lighter air season.
There is, of course, much more to the story as others have alluded to. How the sail is cut, the weight of the cloth and where it is used, the type of foam luff that is installed and more. For the most part for most sailors, a furled 150% is OK in most conditions.