Okay this is not related to The Human Gallery, I'm working with something way lighter at the moment which runs 999fps at ease.
Anyways, it all works like a charm when I play in windowed and native size (640x360). But, if I maximize the window (I have "Resize display to fill window size" selected) I can notice FPS dropping every now and then. These "drops" occurs when I jump for example, and it plays the jump sound. I've tried deleting the sounds and it works fine. However if I'm not maximized all the sounds works just fine, no fps drops.
Another thing I noticed that if I change my windows theme to AERO based, it does not lag. At least the FPS does not drop like it does without.
I believe turning vsync off also "helps" though it's not very nice with all the jaggies.
But yes, weird to say the least! But I'm used to that by now.
Any ideas what could be the cause?