Try to visualize yourself in Obi-Wan's boots. You're piloting a vessel with superior speed and maneuverability. You're trying to follow somebody and keep him in your sights. Do you:
- Push the throttle to the max and zoom right past him?
- Back off and match speeds?
Obviously, you back off and match speeds. Then he flies into a hollow asteroid. Do you:
- Push the throttle to the max and crash into either him or the wall?
- Back off to a safe speed and continue following him?
Obviously, you back off to a safe speed and continue following him. You fly out of the asteroid and he's gone. Suddenly, he's right on your tail, blasting away with repeating guns that pulverize asteroids bigger than your ship and fire at a rate of hundreds of shots per minute. Do you:
- Push the throttle to the max in an effort to put more distance between you and him, even though that will reduce your maneuverability and it would take a long time to get out of weapons range?
- Try to out-maneuver him?
I would think you'd try to outmaneuver him rather than trying to run away in a relatively straight line (remember that if you're running away at greater speed, the same burst from a maneuvering jet will produce a smaller angle change from the perspective of the pursuer).
He scores a hit, and then launches a missile to finish you off. This time, there's little choice. You instinctively firewall the throttle, and try to get away. Is this consistent with the film? Yes. Look at how far away the explosion is when we switch to the view from inside Slave-1.