Go check the runs to see how exactly it should be done.

A1. For A1 you wanna go to the back right/left and fall a bit then wall climb to gain speed toward the end all before the timer starts to go as far as possible.

A2. A2 is relatively simple all that is of mention is the wall run to speed up going toward the crystal.

A3. This level might have you fooled to go around but there is a hole behind you that is the more direct route.

A4. The most direct route is to go over the buildings and then slowly drop on the walls to gain speed till you get to the end.

B1. Just keep to the walls and don't go down the spike tunnel as I believe turning the corner is faster.

B2. Both straight and right are about the same speed I haven't timed them and go down at the end.

B3. You wanna go right at the start then at the next split I believe down is faster and other then that just go fast.