I'm on a mid 2010 mbp, so I am looking for an upgrade. I am having trouble deciding between the MBA and the 13 rMBP. Something that is making me consider the rMBP over the air is the fact that I can have a higher resolution, but I am curious if using scaled resolution actually impacts performance to a noticeable degree. I run some decently power thirsty apps, so if I can have 1680x1050 while doing this, then the main benefit of rMBP becomes moot. I am curious what people's experiences have been. Is there a noticeable performance drop whilst in a scaled resolution mode?