Video file choppy during playback after export

Hi guys. I hope you can help. I’ve edited together a video ready for YouTube. This is my first time using Shotcut. The problem is that when I watch my exported video, it is really choppy in the video player. I’ve uploaded it unlisted to YouTube too and it’s the same on there. By choppy, I mean that roughly every second, a frame will remain on screen before jumping to where it should be (it remains on screen for about half a second). The source videos are fine. Is there anything I can do in the export settings or in the project settings? It’s fairly choppy during playback in the project file too, but I thought that when it became a video file, that would be ironed out?