With all that and the hologram floating around for me to place, everything is fine... BUT the moment i hold down the shift key to place multiple pylons or supply depots or what have, my frame rate drops to the point where my placed buildings doesn't always even register.
The same happens on a smaller scale when giving shift commands to units for other things aka mass snipe... in fact, i could be doing nothing and have nothing selected, and holding down SHIFT slightly slows down frame rate.
This leads me to believe that either
A) sc2 does some kind of extra command checking or w.e when using shift in anticipation or w.e (like as long as SHIFT held down, repeat such and such check subroutine regarding commands) OR
B) my computer has some weird out-of-game process bound to the shift key that runs while i'm playing and causes my computer to unnecessarily multitask.
SPECS:
HP PC - Laptop - Windows 7
Intel Core i7 720QM @ 1.60GHz
4.0GB Dual-Channel DDR3 @ 665MHz
NVIDIA GeForce GT 230M - Driver version 8.17.12.6776
EDIT 1)
My sticky keys is disabled, and the SHIFT key effect has no impact in game menues only in game.