PCLinuxOS Openbox Bonsai and also the latest PCLinuxOS Openbox have compcache configured and enabled with rzscontrol (this can be checked with the command "cat /proc/swaps). Appearantly, a machine with 2 Ghz would be considered here as a real race horse. - "bête de course", en français - . The machine I use each day has a Celeron 1.46 Mhz, with 1 Go ram, which works perfect.
Galen has tested the first one on an older machine too.
There is no other trick in them to speed them, exept the choice for the services started at boot, which are reduced to the minimum usual requirements. (And botth have the latest kernel with bfs... sure).
PS: in my machine, prelink made the hard drive scratch with lots of noise during several minutes each day. I tried it once, during 2 or 3 days and I didn't like it doing that, so I didn't keep it.