
At the end of tutorial island when you talk to the wizard there is an option to change the XP rate.

To Change EXP multiplier:
1. Launch the game and make your character.
2. Close the game
3. Go to C:\{user}\2009scape\singleplayer\game\data\players
4. Where it says "exp_multiplier" - change 5.0 to 1.0