While this is a shock to almost no one, we've never had solid statistical evidence that the chase for faster greens slows down play. Anyone who has some of the best putters on the planet mark 18 inch putts when greens are pushing 14 realizes speed forces caution for even the very best.
The USGA and University of Minnesota have teamed up for some very intriguing Science of the Green studies, and while it's early you have to admire their release of findings from a recent green speed/pace study at Poppy Hills. Parker Anderson explains the methodology, the plans for more extensive efforts and it's all worth reading, but of course we'll cut to the chase here:
An increase of one foot in Stimpmeter reading resulted in an increase of 6.39 seconds per green per player. This one foot increase equates to an increase in total round time of a foursome of 7.67 minutes. In some instances, the increase in time spent per player per green resulted in an increase of as much as 30 minutes per round for a one foot increase in green speed (25 seconds per player per green). Overall, playing experience ratings decreased as green speeds increased. This decrease, although statistically significant, was small.
In conclusion, we found that faster greens equate to longer round times. The strength of this relationship, however, is not as substantial as we had hypothesized.
Perhaps I'm misunderstanding, but I would disagree that the number is insignificant.
On these findings of one foot of speed increase, greens Stimping 9 for a foursome would take 76 seconds less to play a hole than a group dealing with 12 on the Stimpmeter. Over the course of 18 holes that adds up to over 20 minutes. Throw in the added cost, stress and architectural impact, all of which do not improve the game, and the chase for speed continues to make little sense.