I believe the word you're looking for is "slither"...and I don't really know the answer. I imagine that they could surprise you with how fast they could go if they really felt like they had to get somewhere quickly.
I have been amazed by how quick they can move if they want to. I had one female who would literally leap out of your hands; she was an aggressive one, though. One time she jumped somehow, out of my arms and onto this shelf in my kitchen, and I had to think fast! Generally, to me, it seems that the more aggressive and easily agitated Bps move faster. Laid-back captives, especially nice fat ones, never seem capable of moving like a Bp who's good and mad.
-Jen. Back in the hobby after a hiatus!
Ball pythons:
0.1 normal; 1.1 albino. 1.0 pied; 0.1 het pied; 1.0 banana.