When gaming on a standard Full HD 1080P 60Hz Monitor the target Frames Per Second (FPS) will be an average of 60 FPS. This is so that the user will experience smooth gameplay.
If a machine struggles to achieve 60 FPS at maximum game settings then you should lower the settings to allow for that 60 FPS average. If the machine is capable of achieving over 60FPS on maximum settings then the user should enable the V Sync setting in the game. This will cap the game to 60FPS which as stated above is the optimal FPS whilst using a standard 60Hz monitor.