If you have a weak CPU you can improve the performance with DXVK.

Download DXVK: https://github.com/doitsujin/dxvk/releases

Unzip it with 7-Zip or something.

Switch into the x64 directory.

Copy the "dxgi.dll" and the "d3d11.dll" into the FF14 game directory. Not the boot directory.

Start the game.

Now the game uses a DirectX 11 to Vulkan warapper and it should run noticably faster. If you get some glitches or the game does not start the delete these dll files.

Cheers