Regarding specs, pretty much all the work is done by the graphics card so that rings true, I'm running dual core 2.8 with 4 gig ram and Win XP, with ATI radeon 3400, 256 meg graphics card, most stuff runs very well on it despite being pretty old...
Definitely get rid of the text objects, as you say global var will cover that.
A text object to show Construct 2's FPS calculation, would be a good idea though, as fraps itself could be eating into your performance...