Curiously, not as much as you might think. I was reading that Andy Roddick had the tip of his racquet moving at 120 mph on serves in the late 2000s. That’s comparable to clubhead speed for pros on the driving range.
However, the speed of the center of the racquet where the ball strikes is less, probably no more than 100 mph. The fact that his serves topped 150 mph leaving the racquet had to do with the elasticity of the balls and the strings.
Different tools are in play (pun intended).
Club head/racket speed, plus rebound speed, plus ball size, surface, and backspin equals distance.
Comparing a 43" driver striking a golf ball with the club’s head to a 29" racket with a 16" long head (sweet spot being 7-8" from the tip) is an interesting experiment.
The rebound speed of the various compression-rate golf balls is well established. But what is the rebound speed of a 1.62 ounce, 1.68 inch diameter, 100 compression golf ball from high/low tension tennis rackets? IIRC, low tension string produces more rebound?
My limited research is that a PGA allowable driver can’t go above .83 coefficient of restitution (COR)(spring effect) and a tennis racquet would normally be a COR of .90-.95. You have your orders, math geeks.
Actually that would make it more than I think. The sweet spot on a driver is closer to the tip than on a tennis racquet. So it’s length is even more of an advantage. With equal tip speeds, the “sweet spot” speed of the driver would be faster.