FCP X slow when editing
I am having problems editing a simple video. Currently I have four simple clips, each about 6 seconds long. The spinning rainbow wheel appears for a few seconds when I move to a different part of the time line and play the video from that point. If I use the cursor keys to move the video a frame at a time there is a brief pause. When playing back in the time line and moving from the third and fourth clip the video freezes a second before the edit and a second after. I tried all this on the timeline of a video I made a while ago and none of this happens.
I'm using a MacBook pro early 2015, 2.9 GHz Intel Core i5 processor, 8 GB memory and a Intel Iris Graphics 6100 1536 MB. OS is High Sierra 10.13.6 FCP X is 10.4.3