When using the Pencil tool to draw MIDI automation, the data is drawn as a series of discrete steps. You can control the resolution (or density) of these steps to help manage the amount of MIDI data sent for a given MIDI controller move.
The illustrations below show the same MIDI controller automation drawn with different Pencil tool resolution settings.
For better performance, consider selecting a smaller value for MIDI controls that need higher resolution (such as MIDI volume), and a larger value for controls that may not require a high resolution (such as Pan).