I forgot where I read it, but I remember reading somewhere that the fastest measured speed is about 17 miles per hour. That video showing the ball moving at about 10 miles per hour on Johnny Mnemonic sounds about right in regards to that.
Bear in mind that the ball can appear to move faster than it really is because things in a pinball machine are miniaturized. Hence, the ball can appear to zip past things in a small, enclosed space. You see the same effect when riding roller coasters: Unless you’re on one of those extreme ones at Six Flags or such, it’s going to top out at about 25 miles per hour. It just feels fast because the track is narrow and the turns are sharp for the speed they go at.
Meanwhile, the opposite happens (and according to traffic analyst Tom Vanderbilt, is completely intentional) when you’re driving down a highway. You are going WAY faster than 17 mph or 25 mph, but it doesn’t feel like you’re zooming down at breakneck speeds because everything on and around a highway are oversized. Signs take the form of big bright shapes you see slowly approach at a distance and move past you. Same with trees by the side of the road and call boxes on those big poles. If you’re a normal person, you likely severely underestimate the size of these things on the road, and your brain perceives you as going much slower than you actually are. (For instance, those dividing dashed lines between lanes–how long are these dashes? 2 feet? 3 feet? They look like that to me. They’re actually 10 feet, with 30 feet between dashes.)