It's funny, after all these years I still find the slow-motion running of SMDM to be more thrilling and believable than any of those CG "super speed" effects I've seen on shows like The Flash or Smallville.
I'm not sure the FX on The Flash
were CGI. It was a little early for that. More like video compositing of live-action elements, 2D video animation for the blur effects, and a lot of old-fashioned stagecraft and camera tricks. Basically the same level of FX technology you would've seen on ST:TNG (in fact the show's FX supervisor David Stipes was a TNG veteran).