What effect does icing have on an aircraft's performance?

Icing has a significant impact on an aircraft's performance primarily by disrupting airflow over airfoils. When ice accumulates on the wings and control surfaces, it alters the smooth flow of air that is necessary for generating lift. This disruption can lead to an increase in stall speed, reduced lift, and a decline in overall maneuverability. The presence of ice not only affects the aerodynamic properties of the airfoils but can also lead to larger pressures on control surfaces, making the aircraft harder to control and increasing the risk of stalling. Understanding this effect is crucial for pilots in managing aircraft safely under icing conditions.

The other options reflect concepts that do not accurately describe the impact of icing; it actually increases drag rather than decreases it, does not enhance fuel efficiency (as performance penalties lead to higher fuel consumption), and does not reduce engine temperature, as icing generally does not have a direct positive effect on engine performance.