Im at a loss. I have 24 GB of ram and when I use Final Cut Pro X, it literally uses up all my memory and causes my 2012 Mac Pro to come to a screeching halt. I've closed out all other programs, deleted all the unused render files, deleted backup files and cleaned out the cache. I've done this before and after a day or two, Final Cut Pro would run flawlessly for about a week or two and then I would have to go through and clean up all the junk. I've even recently tried sending all the files and cache to an external SSD drive...and still it's using all my RAM. If I can't find a solution I'm giving up on Final Cut Pro and going to Premiere.