Because it spontaneously resolved for me, and I want it back! I hate walking so slow. It makes the game really boring. I miss turbo walking.

(full case report:
initially, I noticed turbo walking and CHOPPY ANIMATIONS. High framerate, though. Turbo walking was more turbo at low resolution (640x400) and less turbo at native res.

Then, I rebooted, for unrelated reasons. Suddenly, choppy animations became smooth animations, and turbo walking became slow, methodical walking. That brings us to the present.)

It is related to your computer uptime, I've fixed it in the "unofficial patch". I must admit I got used to the bug myself, but as I never reboot (hibernate) I got to a point where it was unplayable :P

Not to spoil anything but later on you'll be able to run faster.

Did you try Nuky's unofficial patch mentioned here?

Yup! Thanks for the response, but that is the patch I tried last week! :)

You are a GENIUS. Thanks! (also, how the eff did you fix it in the unofficial patch? i imagine you had to wade through an ungodly amount of code to even figure out where the problem was.)

@Waltorious--
I think there are actually two, distinct types of turbo walking. One is constant turbo walking, which, as Nuky states, correlates with uptime. The other is the sudden "lurching," where your character pauses for a second, and then zips forward as if to catch up with himself. This is still happening to me even immediately after rebooting. Not sure if there is a solution.

I'm not sure yet why that "fast forward" thing happens (try quicksaving while walking). This is on my priority list, if I ever motivate myself to continue working on the unofficial patch ;)