Levitation and Gravity

I have a few boxes. On the lower-end ones, levitated characters "sink" to the ground a noticeable amount faster than do toons running on better hardware.

Any ideas what might impact that?

memory and CPU speed

Make sure they are looking up, and check the max fps is unlimited. Especially when tabbed out.

level 115 Vah Shir beastlord, even looking up I sink like a rock. I've seen others stay in the air a lot longer than I do.

Memory 8 gig
cpu I5 intel. 2.67 GHz

Frame/refresh rate settings in the Options page - can't check at the moment, but from memory, setting a lower refresh rate reduces the rate at which you sink, so it's a balancing act to get a rate set that is still playable, but doesn't sink as fast.
There are also different sliders for when the EQ window is foreground/background - I usually set them the same /shrug

There are two ways to sink faster: low FPS and higher weight.