starcraft lags in full screen mode but not minimzed mode, hardware issue?

hi
recently ive noticed that starcraft ( fully updated ) in fullscreen mode lags incredibly, pratically beyond being playable, im not sure what this is due to, but in minimized mode it plays just fine, the game is really old and i dont really see any software reason for this.

here are some relevant notes

my computer was affected by the nvidia issue and the part was replaced less than a year ago, so i dont think its the video card, or could it be?

my computer has been heating up a bit for like 3 months, i recently downloaded the smc fan control to control that and its been fine since then

i ran the hardware test that came with the comp and everything seems to be fine

i ran techtools pro too and everything it checked seemed to be fine

dont know what else to say, this kinda confused me, if anyone knows anything, i would be greatful