What is the amount of performance difference between having a 3 or 6mb L2 cache? I'm getting a new MBP soon. Originally I was going to get the high end 15" with the 512mb discrete graphics but then decided that I didn't really need it after reading a thread where most people said they don't even use it and just kills the battery. So Then I decided to move 2 steps down to the low end 15". However it only has 3mb of L2. Are there any noticeable differences (not taking into account GPU or having a lower cpu)?