When Flaca steals the satchel containing the $2 million and is chased by The Man, she runs as if the bag is virtually empty. In fact, $2 million in 100s (at 497 US bills to the pound) weighs over 40 pounds, and the heavy satchel (about 1/3 of her estimated weight) would have slowed her down considerably. The weight of the bag would also have likely drawn the interest of the thugs who throw it at him (again, as if it weighs about 5 pounds).