tl;dr - I want to be able to disable thumbnail on the timeline. How do?
If I open Shotcut, open a video, and begin editing away, it is glorious. If, for any reason, I close Shotcut and reload my project later, my edit skills get grossly laggy because 80+% of my CPU gets dedicated to making a thumbnail after splitting the video for the next 5 minutes… every single time I make a split (which is a lot). I don’t use the thumbnails anyways so I want to work around this issue by disabling them entirely. Can I do that?
Yup! That’s it! Too bad it didn’t help though. I don’t know what Shotcut does different from a fresh file and a saved project, but the difference is HUGE in performance. Driving up the CPU to over 80% for several minutes so I can no longer preview the video until it’s done is not acceptable.
I do not generally experience the problem you describe unless I choose a known slow format like Cineform. Maybe it is due to the format of your clip. It may not be edit friendly. You can try using Properties > Convert on it.