I watched this YouTuber, editor, doing things on shotcut and they mentioned,even on their 2000 dollar pc the preview window in shotcut wasn’t showing clips smoothly. I get this too, I would really appreciate it if this preview window could be improved…
There has been vast improvements with Shotcut.
Here is one of them.
It still might come down to what your computer can do.
Not sure what your computer specifications are, but there are minimum specifications to run Shotcut.