The act of turning while simultaneously moving forward creates a centrifugal force that is directed away from the centre of curvature of the turn. Newtonian mechanics dictates that the magnitude of the centrifugal force is proportional to (a) the curvature (the reciprocal of the radius of the turn), and (b) the square of the speed. Hence, the sharper the turn, and the higher the speed, the greater the danger of losing control. ~ Indian-born Australian biologists Mandyam Srinivasan & Mandiyam Mahadeeswara
The craft of flying presents many challenges, including takeoffs, turns, and landing. Turning during flight is especially tricky: requiring exquisite coordination to ensure that the resulting centrifugal force does not disrupt the intended turning trajectory. The centrifugal force depends upon the flight speed and turn curvature. To limit centrifugal force to a manageable level and prevent sideslips, sharp turns necessitate lower speeds.
Bees, bats, and birds all naturally optimize their flight to achieve the fastest possible turns given the mechanics imposed by gravity. Bats and hummingbirds are especially impressive in their pinpoint turns during flight. How intention translates into physical movement is itself astonishing, let alone maximizing performance from a physics standpoint.