4k video will not render on timeline

Thanks Tom. I think I've been confused about render files. I did a bit more research after reading your reply, and you are correct. I was under the impression a render file would be created to any file that could not be played back smoothly (ie: 4k on a 2011 mbp). Turns out, render files are only created once any change is made to the clip.

I guess I need to look into using proxy files or optimized media, which I've never used before. I just loved how seamless the rendering process is. No proxy files, done automatically in the background, etc... I wish there was a way to force rendering of a 4k clip on a 4k timeline.

That's my problem, my 10 year old mcp won't play back 4k smoothly. I've been playing around with proxy files, and that has solved my problem. Playback is super smooth, and switching between proxies/originals is very easy. Man I love fcp. Thanks for your help Tom, I really appreciate it.