The ≈60 FPS figures for Quake 3 on Pegasos, iMac G5 and AmigaOne X1000 suspiciously look like they might be the result of enabled vertical sync with the 60 Hz monitor refresh rate. It may be coincidence, though.
Pegasos & iMAC vertical sync was disabled - acc. to this post
AmigaOne X1000: I don't know exactly, for testing I use ioquake3
. I used the same settings like for MorphOS, but "setenv TGLSYNC 0" maybe have no effect on AmigaOS.
Also relatively poor results of powerbookG4 and iMacG5 can be caused by running the test in resolution (1600x1200) bigger then native resolution of their displays.
Pegasos II 1.33GHz, AmigaOne X1000, Powermac G5 Quad, iMac G5, Powerbook G4 and Z10PE-D16 WS
MorphOS, AmigaOS, Debian, Ubuntu, OSX, NetBSD, Win7