I recently went to an arcade and my wife and I actuually said the opposite of what you said ...we thought it was too fast. Well after doing some investigating I found out that there is a speed up chip that was available for the game.
Therefore my guess is that you must have played the speed up version and I must have played the original,or slower version.
BTW...I just played the rom mspacman and that seems top be the speed I remember
Just my 2 cents
Ed