The choppy playback on the timeline occurs mostly by the files with a high Bit Rate.
Most files coming directly from an HD camera or Drone have a high Bit Rate, such as MOV and MTS files.
But generally, the output video quality will not be affected.
As an alternative, you can try to transcode the imported videos to.MP4 before loading to our program. The whole re-encoding process will help you reduce the high Bit Rate and keep the video quality.