Best way to upgrade macbook for video editing

I have an early 2015 macbook pro (retina) 13 inch with 2.7 GHz Intel Core i5 and Intel Iris Graphics 6100 1536 MB. I'm also a video editor. I'm going to be editing 4k footage soon and I'm worried my laptop won't be able to handle it. Is there any good way to upgrade my computer by adding stuff on a budget so it can handle big files? I could definitely proxy edit but I'm worried it still will be super laggy and hard to work with. Also, they're considering using 4:4:4 color space, and I'm not sure if that will affect it either. Do I just need to get a new computer? It's about time anyways, the screen is cracked and there's a huge black chunk at the top... Thanks!