I believe they switched from Bermuda to Bent grass in 1981. I assume that was the big watershed. By 1986, they were clearly very fast. That famous Nicklaus putt on 17, looked about as fast as the current setup.
It is also interesting how many short putts were missed back then. I don't know if that was due to the Bermuda, or just pressure, or instruction/technology, but there were some God-awful strokes made on short putts. People still miss short ones all the time, but they usually don't look quite so doomed right from the start (think Doug Sanders at TOC).