It runs smoother with the following Logic Pro X audio settings:
Processing threads: Automatic (Recommended), before it was 10 (8 high performance cores)
Processing Buffer: Small, before it was Large
Multithreading: Playback & Live Tracks. before it was only Playback
Changing the multithreading setting has produced the most noticeable difference!
Further information about the multithreading function: (maybe helpful for the problem solution)
You can use multithreading to affect how Logic distributes the DSP load when a software instrument track stack is selected for live input or when multiple audio tracks are enabled for recording.
The Playback setting reproduces the behavior of earlier versions of Logic. When a track stack is selected for live input, or when multiple audio tracks are recorded, all of the DSP required for the input is processed by one processing thread-and thus by one available core on the computer.
The Playback and Live Tracks setting distributes the load across multiple threads when a track stack is selected that contains multiple software instrument channel strips, or when more than one audio track is being recorded. If the computer has enough cores and there are no other DSP demands on the computer, each live channel strip can be processed by a different core.
With the Playback and Live Tracks option, the system may be a bit more stressed. So if you don't have live tracks with high demands, track playback may be a better choice.