Maia doesn't need to be faster than GSP to take him down. He probably will just run toward him and get himself glued to a limb and advance from there. Basically we have seen what he'll do recently.
It's not just speed, it's footwork and range control. If he tries to rush GSP, he'll just get side-stepped and eat a punch or 2 for his troubles. He'll need to set it up and somehow corner GSP against the fence, and this is a complete bitch to do since GSP has excellent cage awareness and always circles out and back towards to the center as soon as he gets behind the black line in the octagon. GSP's TD defence is incredibly good, and his footwork and range control takes it to the next level by making it very hard for his opponents to get a good hold of him.