What spec is your macbook?
Do you have to turn any settings down?
What size external screen are you playing on?
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I keep hearing allot about this iRacing.
Why would i play this over GT5 or Forza 4?
I have a awesome steering wheel ready to be used on a new racer .
If it will run smoothly on my Macbook on a 37" tv i might give it a try.
its a i5 MBP with 2gb ram. I just play it on the screen itself.
Why would you play this over GT5 or Forza? This is a driving simulator, those are arcade games.