This is about user perception of performance: startup time, UI responsiveness, etc. Not raw CPU speed. It did fine on all those counts, even if you'd never let VB do your DSP work for you.
Granted, the platform surrounding VB6 arguably had too much hairy logic related to COM and ActiveX, and the fragile system that existed for registering such components before Windows XP introduced side-by-side assemblies. If you really want to pine for the old days, consider Delphi, where you could compile everything into one executable; just map that hunk of code into memory and go.
You wouldn't crunch numbers with it, but it was responsive and fast enough for most purposes, and had simple interfaces to faster native libraries for a lot of the rest.
>> These crappy amateur applications were downright speedy.
Compared to what? Visual Basic performance was a joke, even when you compiled it to native code.