All I was comparing was first boot into Slack 9 vs first boot into Slack 8.1:
Same configuration
Same ReiserFS
Same services

Fonts were worse, and that seeking of my harddrive was definitely abnormal. Mandrake 9.1 has same gcc compiler as Slack 9, and I believe the same version of KDE, and with the same services running and ReiserFS, it absolutely flies. Frankly I was very surprised... I expected it to feel bloated. And my harddrive is back to normal.
I've installed and used Debian, Knoppix 3.1 and 3.2 (2 versions of the latter), Redhat 7.3, Mandrake 8.0, 8.1, 8.2 and 9.1 Libranet, Elx and College Linux. Used ReiserFS whenever possible and EXT3 otherwise. Until Mandrake 9.1 came out, Slack 8.1 had the best "feel" of any of them. I just can't say the same about Slack 9.