To summarize a longer discussion in PM.
The NCS X can be seen as the NCS Service + NCS windows client. This means that The GUI in NCS X should be treated as the windows client. In the Settings you have Client Settings. When adding a camera the the GUI is by default in Multi-View even if only one camera is connected. In the settings the default value for Multi-View Refresh Rate is set to 10 FPS. Change that to 20, 25 or 30 FPS and Save and you will have what the camera can deliver. This value is then valid for all cameras.
To get to the Single View mode in the windows client/NCSX click here and select the source.
Now the background will turn to white. In Multi View that background was black. In this mode the FPS is set to 30 FPS by default, but can be changed with the Single View Refresh Rate as in the first figure.