Not Square-Enix support or anything here, but...

I see you have Wallpaper Engine installed; out of morbid curiosity, are you running it? I had horrific performance issues with FFXIV in borderless windowed mode—hanging the system, freezing other programs entirely, etc.—until I turned my desktop wallpaper static; I don't know why on earth it was so badly affected by that, but those two programs did not want to play nice with each other.