On my comp (2ghz), looking at the second demo, I get 53 fps if I stare straight up at the sky, about 23 fps just walking around any of the buildings (relatively near starting area, view angle along the horizontal). It varies from 19-25 but mostly around there. Not sure how someone's 2ghz laptop is beating me? Are you using the small version or the large one (I'm using large).
reasons can be : JVM,Video Card, processor brand, or a background process eating cpu.
On my 1.6 Ghz (brand:AMD 2000xp+) with ATI x800 : I got 70-77 fps when I look to the sky and around 28-35 fps every where else.
Usualy videocard do not make a big difference because it is only used for blitting in software renderer, but there can be a difference between a very old videocard and a recent one, blitting final image can take 5ms in last videocard and 10ms on old one. I expect the difference may come from your videocard?
looking at sky is like filling the pixel with a texture and blitting image to the screen : you got only 53 fps on a 2Ghz when I got 77 fps on my 1.6 Ghz, I think videocard do the difference.
EDIT: be sure you will get a decent framerate in the next API version ;-)