I don’t expect speed increases from operating systems but from hardware and drivers.
I just overclocked an XP box from 3GHz to 4GHz CPU speed tonight. Wow. What do you know. It’s “snappier”.
A newer hard drive with a lower access time and double the cache. Hey. It’s “snappier”.
I then put three of those hard drives in a Raid 0 and more than tripled my throughput. Hey. It’s “snappier”.
Computer tech writers are in permanent cranial/rectal inversion mode.
You haven't been using a Mac. Every OS X release makes things run "snappier" on the same hardware. I upgraded from Tiger to Leopard (in place upgrade!) and I'm happy about the speed improvement, and I can't wait to extend the life of my iMac even further by installing Snow Leopard.