To edit and view UHD video requires the latest and greatest technology. More and more people find this out after buying their Phantoms and GoPros (or whatever). Sure, having your current system up to date is important but has its limitations. You can compress your 4K files but it will come at a cost. You may as well shoot lower resolution at that point because your computer, tv, YouTube (to name a few) can't view 4K (unless you have the latest tech). Even with the latest hardware, tech sites like YouTube will still dumb it down. Then, after buying that new computer you need to shell out more money and invest in a program like Adobe Premier Pro or the like and learn how to use it to make those videos look great.
When I started messing with video my video was choppy too and it was a frustrating process to edit on my computer. Once I got it done and taking forever to render and upload I could finally see what it looked like by watching on YouTube. Needless to say that process took all the joy out of my new hobby. Now it's a much better experience after upgrading my computer.
Just like any hobby... The more you get in to it the more it costs. But hey, it sure is fun!!