You should also combine Preview Scaling with Proxy to really eliminate as much lag as possible:
Preview Scaling handles the lag that comes from adding filters. Proxy only takes care of making the videos files you are working with less of a burden on your computer. So if you are running on a slower machine make sure to use both at the same time. It’ll definitely allow you to use your current workstation for a much longer time without having to buy a new one. Try both Preview Scaling and Proxy and let us know if they give you a better editing experience. You’re up to date with the latest Shotcut version, right?
And thanks for sharing your videos. They are well made and a good representation of the quality content that can be made using Shotcut. It’d be cool if you put in the video description you’re using Shotcut to help spread the word.