Good morning! Thank you for posting in the Final Fantasy XIV Technical Support Forums.

Please try the following:
Open the Nvidia Control Panel and going to 'Manage 3D Settings'. From here, select 'Program Settings' and select Final Fantasy XIV. You should see an option to select the GPU. Make sure it's set to your dedicated graphics card (it may be set to 'Auto' by default)

Delete locally saved content ('Documents' > 'My Games' folder), if you use OneDrive the path would be 'OneDrive' > 'Documents' > ... instead.
When the game is running, open the task manager, click the ‘Details Tab” Find the game and right click it. Select ‘Set Priority’ options to “High”

Double check to make sure PC is not over heating and remove any overclocks on GPU/CPU.

Could you try using a registry cleaner such as CC cleaner? It will run and remove files that may have been left behind by installation and other activity on the PC. To so, please remove the game and then restart the PC. Run the registry cleaner and then restart the computer. Once the computer has been reset, please reinstall the game again.

Go into your power settings within Windows and select additional power settings. Change to maximum performance then save the selection.

To disable DirectX 11, simply visit the 'config' section in the FINAL FANTASY Launcher and toggle 'DirectX 11 Support' off.

Thank you once again for visiting the Final Fantasy XIV Technical Support Forums!