Even with the recent OS X v10.0.1 upgrade, we're at a rather early point in the life of OS X. We can expect a bit of additional speed with each minor upgrade Apple releases, I'd wager. But I was surprised to note that, in working with my NeXTSTATION Turbo Color workstation (68040 @ 33Mz, 32MB RAM, running NeXTSTEP v3.3) this weekend, NeXT applications and the OS in general do indeed feel significantly snappier on this machine than OS X and its apps do on my b&w G3 400 (256MB RAM, UltraWide SCSI). This is especially interesting to me given that I've recently been working with a PowerMac 6100 (PowerPC 601 @ 66MHz, 32MB RAM, 1MB L2 cache, running MacOS 8.6) which just feels super-sluggish. And it's CPU is much faster than a 33Mz 68040, and OS 8.6 is far less complex than NeXTSTEP--one would think individual apps would feel faster, but they do not.
OS X has its sluggish Aqua, NeXTSTEP has it's sluggish Display PostScript. They both run a Mach-based BSD implementation. Lots of interesting angles here. Perhaps in relative terms, the NeXT hardware was more on-target.
What do you think about that?