Final Fantasy Tactics: The War of the Lions

[tet666]

Is there any way to get xbrz texture scaling to work on pc without it becoming a slideshow every few seconds?
Im running a overclocked i5 with a gtx 760 and i still can't maintain full fps with it on, it goes to ~5 fps every time a spell is used (slowdown patch is applied ofc) or any other effect is shown thunder in the first stage for example or the area transition effect before the first fight.
It runs perfect with scaling off but i would really like to use it since it makes the game look really great.