The speed of the clubhead at impact is determined by the sequence of body movements throughout the golf swing. The idea is to get the wrists to unhinge precisely at the right time and at the fastest speed possible. There is one optimum way to go through this sequence of body movements and a whole bunch of not so optimum ways. In order for the wrists to do their job they must remain loose and supple throughout the downswing. Lag or if you prefer drag, depends on the weight of the club to keep the wrists hinged as long as possible on the downswing. This can only be accomplished if the wrists are relaxed. When the sequence is properly executed the inertia of the clubhead will unhinge the wrist precisely at the right time sending the golf ball long and straight.
2. Start the backswing by moving the triangle that is formed by the arms and shoulders back until the club is waist-high. Keep everything relaxed with your upper arms close to your body. Keep the wrists (do not hinge) and hips quiet.
3. Start activating (hinging) the wrists. The club should reach 90 degrees to your left arm when the arms are about shoulder-high. This is the only time in the sequence that you should consciously manipulate your wrists.
4. Finish the backswing by turning your shoulders until your back is toward the target. If you do this properly the left arm should be straight. If you don’t get a full turn them most likely the left arm will bend at the top of the backswing.
Let the torso pull the hips to the right while maintaining a balanced position from the waist down. Any hip turn, left knee bend and weight shift should stay within the confines of the shoulders. Remember that the shoulders turn. There should not be any lateral movement of the shoulders as you turn back.
5. Start the downswing from below the waist. That is, start turning your hips and weight towards the target. This is the most important part of the downswing. If your wrists are relaxed then it will feel as though the weight of the clubhead is holding your arms and shoulders back. The angle between the club shaft and the left arm will be maintained until the inertia of the clubhead starts to take over. When it does the wrists will start unhinging. As this is happening, keep your left arm close to your chest. This will ensure that the club shaft stays on-plane.
6. Keep turning the hips toward the target and let the wrists unhinge through impact and the follow through. There should not be any conscious effort to manipulate the wrists during the downswing.
There are a lot of mechanical body actions going on throughout the downswing as outlined in the above steps. Obviously, you cannot think of all of them while swinging. The idea then would be to practice the sequence slowly and try to understand what each part of the swing feels like. As you gradually increase your speed, start thinking about how the whole sequence feels rather than the individual parts. Eventually, you will understand what a good swing feels like and be on your way to hitting good golf shots.