I have a 30 sec commerical I am working on. It does have a number of native effects (3d warp, paint, spectremate) in it. But geez why when I render the whole timeline do I have to render the whole timeline again when I do something to 1 clip. I can never get any smooth playback. Even when I close out of MC and comeback the next day, I have to rerender the whole timeline again.  Its 1080 footage, not 4k. Does anyone else have this problem. 

Hard to say without knowing what version of Media Composer you're using, or anything about the computer you're using it on. If you fill out your system specifications in your profile you won't have to do it on every post.