The older I get the slower I get. Really stinks!!!!! But I also find that I have learned to be calm. That allows me to move when Uke thinks about entering my space. I have found that when I attempt to move to quickly, some degree of control is lost.
Attending some of Ikeda Sensei's seminars, he often talks about beginner technique and advanced student technique. He will demostrate the same technique showing how a beginner performs it and how the advanced student performs it. Sensei is not moving any faster in either demostration, but the advanced student technique is done much more quickly because the movements are much smaller and more precise.
Just my observation.