Hi Kenny. Thank you for you videos.
I seem to have found a workflow for complex (with envelopes, animation, and effects) 4k video editing in Reaper DAW. I haven't tested it thoroughly yet, but I'm writing in the hope that if I'm mistaken, knowledgeable people will advise me. The workflow is based on proxies.
I create proxies using Davinci Resolve. I place the original 4K videos in the 'Original' folder and drag them into the Davinci project, specifying the desired proxy resolution in the settings (1/4 in my case), the proxy folder (with a clear name 'Proxy'), and the codec (H.264). I select all project files, right-click on it, and ask Davinci to create proxies.
I wait for it to finish, close the program, then open Reaper, set the project settings to the proxy resolution, and work with the small files. When I'm done, I change the project settings to 4K and close Reaper. I rename the Proxy folder, open Reaper, and in the dialog about missing files, I point to the Original folder. That's it, hope it's understandable.
My previous 4K videos made in Reaper were much simpler, so I managed without proxies. Here's an example
https://www.youtube.com/watch?v=hvJfk293xpI . Now, we're creating 'The Final Countdown' with a green screen and 'space-age' effects. My computer can't handle it. May be I should use Davinci for all this project, but I know Reaper pretty well (thank you Kenny), and I love working in Reaper.