PaulisDead2221 said:
As long as your video editing program has multiple video tracks, this will work. I put the 1080p version on video track one, then above it, on video track two, I put a 480p version of the same film, frame accurate to the HD version. I then set video track one to be invisible, and just made sure that every change I made to my visible 480p footage, was also done to the 1080p version. Basically, every edit you make is made twice, then when it was time to encode, I set video track one to be visible, and video track two to be invisible. It still slows things down excessively, but only during the final encoding stage. I'm not sure if this information may be helpful to you, or how stressful, if implemented, it would make editing with all the color correction/fx layering you do (which I would imagine takes up more than two video tracks). But I thought you might find a way to temper the method to make 1080p editing work for you.
Interestingly, this is basically how movies are edited. A 480p version is edited on a computer that has timecodes stamped into it. Once that's done being edited, it's taken to a ridiculously powerful workstation, and there the 480p version is recreated identically in 2k or 4k, then printed to film. The 480p edit is an "off-line" edit, and the 2/4k edit is the "on-line" edit.
Just a little tidbit I thought may be interesting.