I just tried it and it definitely speeds up the round. I made sure it was tuned off on the greens, becuase I didn't want to lose that visual feedback on the pace of the green (not that it matters much with my putting).
It was very noticeable off the tee and subsequent shots- the ball almost seems to be on the ground before you finish your swing.... can't eevn imagine how fast the higher boosts would be.
The one place I really didn't like it was on approach shots. I'm sure that I'm not the only one who tracks the ball through the air, following the ball flight & glancing up & down from the ball to the pin. We do the same thing IRL. With even this 2x boost, you almost can't do that because the camera angles switch so fast. For myself, that really seems to take something away from the game.
I'd probably give it 2.5 stars out of 5. It's kind of cool, but not really my thing.