I have 22 minutes of 4K footage, over around 15 different clips at 25fps, that I have keyed using Keylight. I have made 1080, h264 proxys of these which has definitly helped speed things up when navigating AE.
I am now at a stage where I am creating a sequence with some of the rushes, zooming in, combining wtih solids etc. So far this sequenceis around 45 seconds long, I set a render last night (using all proxys) and its taken 9 hours! Maybe im doing something wrong?
My final output will need to render the original keyed footage rather than using its proxy version, I would expect this to take a long time. I intially thought I could render out everything annimation with alpha still at 4k and import back in. I need the 4k in order to crop into the footage, but perhaps there is a wuicker way?