In 1988, Andre was 18. I'm sure he was pretty fast at that point.
Andre was often noted as having good movement, but I don't think was a "fast" (post teenage years) in the way the Borg or Pete was fast. His good movement came from excellent anticipation and footwork combined with being in excellent shape physically (when he got serious about training with Reyes) and having good, but not exceptional footspeed.
Looking at this:
en.wikipedia.org
I don't see any players I would categorize as slow or not quick. That definitely tells you something. Even Becker was a solid mover, though no Murray or Hewitt or Connors. Here's my initial impressions:
Note - The Big 3 have had such long careers, I'm just going to go with what they were around their "peak" years, roughly. Obviously, older Fed is not the mover than 2004 Fed was.
ATG Top Level Movement and speed:
Borg, Connors, Sampras, Hewitt, Nadal, Djokovic, Murray
Excellent Movement:
Wilander, Edberg, Kuerten, young Fed
Very Good:
Safin, McEnroe, Lendl, Agassi, Moya, Rafter,
Decent Movement:
Becker, Courier, Roddick,
Don't Know: Nastase, Newcombe, Vilas (I'm giving him his #1)
Don't Remember: Kafelnikov, Rios (probably pretty good), Ferrero
This is involves all of 2-5 minutes of thinking, so I could be wrong here. Rough draft.