Hi youngboy. I never tried to edit 4K videos, but my bet is that it would be difficult on any budget machine. But maybe you can try this tool, created by member KKnBB :
I suggest you take time to read the entire topic since the comments contains many questions (and answers) you may ask yourself about this tool.
There is also the installed “Preview Scaling” tool (Settings / Preview Scaling) that could help a lot. It lowers the resolution of the video in the preview window.