Go to the Switch. Place a portal the highest as possible on the wall above the Switch and facing the exit door, and the other portal on the wall next to you.
Prepare yourself beofre starting the timed puzzle, then press the Switch.
Before going through the portal, aim the floor. Pass through the portal when you think this is the good time to go.
Just after passing through the portal, fire a portal just under you.
With the momentum gained, you should go quite far. After landing, move forward as fast as possible to avoid the Electricity Field.
Go to the Chamberlock. If the exit door is already closed, shoot a portal on the white wall on your right, and the other portal just next to the Switch, then activate this last without going through the portal to open the door again.
