My favorite was the time a teaching pro friend of mine was showing me tour swings and timing. He put Ernie Els on screen, then a student. He started both swings together. Els was at impact before the student got to the top. He picked Els because of the perception that Els swing slowly.
I told him he must have a student with a very slow backswing. He then videod MY swing, put me next to Els- almost the same thing, I was at the top, Ernie was at impact, if he started our takeaways together.
In fact, if I remember correctly, Els's tempo was about the same as Nick Price's who looks downright violent to my naked eye. Also about the same as Tigers! I've come to realize Els looks so slow because his swing must be very efficient with no extra movements.
After that, for a while I worked on a faster backswing. It created much more lag, a shorter backswing and usually better impact, but I just didn't have confidence in that tempo and got away from it. As my fundamentals improve, I am now going back that direction.