Instead of a nice fluid movement, chameleons make many 'jerky' movements for each step. The reason for this has to do with camouflage. By making jerky movements in their steps, they better blend in with their environment. Combined with their colours, the movements add to the illusion of a leaf blowing on a branch.
There is a downside to this, which can be witnessed in certain members of Brookesia along with the Namib chameleon: Chamaeleo namaquaensis. That downside is that a slow jerky movement does not crossover very well to a secondarily ground dwelling existence.