A bit of an extreme example (27 years) and you should have bought the Quadra with the co-processor not the Centris ;-) . I have a few import procedures that currently make millions of string comparisons and when the software runs I should be delighted by the speed. I remember rotating pictures at the same time and leaving them for hours.
But as many use computers today – to communicate, as we are doing, 1 or 10 years old doesn't really matter and OS/Security obsolescence appears needed to keep the industry going. I mentioned Word 5.1 as a bit of a joke - many used to rave about it long after OS9 had gone.
The great power of much faster chips will be that things such as more accurate speech to text, understanding and predicting workflows and the like will be possible. That rather than the speed in itself, will be most revolutionary for most.