Hmm.
I find when I play the game in fullscreen (1920x1080 or 1920x1200 depending on if I'm using my TV or monitor), the gameplay/3D sections for some reason fall to a locked 30fps, and there is a very high likelihood of the game of the crashing after battle.
But playing in windowed mode, the gameplay/3D sections play at a solid 60fps and and has so far been stable that way (no crashes).
Though I noticed that if I alt-tab out of the game while fullscreen in a gameplay/3D section, and then go back, the framerate suddenly jumps to a locked 60, and the game becomes seemingly stable, same as windowed mode. Weird.
(Windows 7, Core i5 760@3.5GHz, GTX 760, 8GB RAM)
EDIT: At some point the 30fps lock and instability both return while fullscreen. alt-tabbing fixes it again, but that's annoying to do repeatedly. Not sure about windowed mode.