Your system is not a problem.the problem is in the game.bandai namco does with all ns games.
If u want to play the game with fair fps.
First open the configuration file of nsuns4. If it has one.
Then you will have to find height and width set the hieght to 800 and width to 720.
If that doesn't works then bring it down like 720 and 660 or 640.
But if ur graphic card does support that much and u r not seeing any lag then u can rise its width and hieght.
Thnx if this works then plz pic it as a solution