There are couple of things that can affect the smoothness of the live view.
Check if you have recompression enabled on the server and if the client is requesting a recompressed stream. To check this, you have a setting called Avoid recompression in the server settings (under Connections -> Local server) and a setting called Request recompressed video on the client settings (under Connections -> Your added remote connection -> Additional settings).
Check if you have the Decode only keyframes setting enabled from the settings of the camera you're viewing (Settings > Cameras > [name of the camera] > Additonal features). Enabling this setting can cause the frame rate to drop due to motion detection and drawing only being performed on keyframes. All images are still recorded when motion is detected.
For more information about the Decode only keyframe setting, see Reduce CPU load.
Check the CPU load of the server and clients when live viewing to see if either of them is at 100% – this could also cause a non-smooth live view.