Ever since I started playing this game I'm having really low FPS and I really can't figure out why. Trust me when I say that every option on my "Graphic settings" is either turned off or set on the lowest.
I'm forced to play in "borderless window" mode because in full screen the fps drop at 8/10. Even with all these precautions my FPS never go past 20.
Plus when I see the boss casting AoEs or when I see them on the ground it's already too late for me to move out, even if I see videos on youtube of people reacting to AoE MUCH LATER than me and getting out safely(ex. Titan's landslide or plumes: if I'm inside when he cast them, no matter if I run out -without Sprint- I am sure I will get the damage, the only way I can avoid them if I'm already in is activating Sprint). Plus when I am still and I start moving sideway it usually take at least half a second before my char actually moves.
Furthermore when with my BLM I am at 3 stack of Umbral Ice and I cast Fire III the casting time bar is always messed up for the next 2 fire skills... like if the casting bar tries to apply the "faster cast" of first fire skill even to the second and the third while the actual animation is acting normally...

My computer has:

Intel Core i5-2320 @ 3GHz
8GB Ram
Nvidia GeForce GT 620 2GB
Windows 7 64bit