Software was already far down the bloat path by the time the Core 2 Duo came out, so the upgrade didn't make all that much of a difference in feel given how much latency was caused by software performing random reads off a disk. That's why SSDs made such a huge difference.
Back in the MS-DOS days, the amount of data needed to be read off a disk while the OS booted was negligible, so a second or two on a fast 486 felt amazing compared to the incredibly slow grind of watching code execute on an 8086 or slow 80286. Software was still in the space of having to run tolerably on an 8086, so the added resources of a newer faster machine actually did improve the feel of the system.
