Assuming anyone actually cares about these movies anymore, I was watching both of them the other day and realized something. Why is it that in the first Transformers film, Optimus gets his metal behind handed to him by Megatron, but in Revenge of the Fallen, Optimus wrecks Megatron and multiple Decepticons during the battle in the forest. It would be safe to  assume he could've handled them all if Megatron didn't backstab him. 
 
Any theories? 

I though of it as he was holding back in the first film because he was in a city with people all around him and didn't go all out for fear of accidentally killing people whereas Megatron didn't give a crap about the humans while in the second film he was in a forest with no people around so he didn't have many qualms about cutting loose and so he was much more impressive.

As a side note, this belongs in the Optimus Prime forums.

cause megatron was in a weakened state......i guess

Prime wrecked Megatron 3 times in the films. I'd say their first encounter was Prime holding back trying to reason with Megatron. On another note: I'm not sure why Prime wanted Sam to push the Cube in his chest either, if that happened, Megatron would still be alive and dominate the Earth.

Basically this, it looked like he was barely trying in the first film.

Maybe Prime was hoping that Megatron would leave earth if there was nothing of interest to him there?