Like the guy from Homestead said... they can move pretty fast...
They also have one other trait that makes actively hunting them in warm weather not much fun at all... Biologists that study them (the Park is probably going to study them until we're all up to our butts in pythons... but that's just my personal opinion...) tell me that the darned critters will coil up loosely on wet/dry plains right out in the open. The problem is that even a big one blends in so completely with its surroundings that you almost have to step on one to find them -when they're not moving...
For the fellow that says there's a bounty on them... Please name the agency and how much they're paying per snake (and do they want them alive or dead -dead would be my preference). While you're at it, if there is a bounty... I'll be astonished if Everglades National Park participates or would even allow that sort of activity (and there's lots of gladesrunners that are very capable of bringing in bags full of the things when it's cold).
Unlike all the popular speculation about snakes eating your pets... the real problem is how badly the things affect any local predator population. They're taking the food bobcats, foxes, hawks, and eagles need to prosper. Not enough food and their babies don't survive... I think things in the Flamingo area are in really bad shape (that's where many python are sighted most days...).