Even though I switched my project to a laptop with 8meg of RAM on a 64 bit i7 computer, I still get lots of freezing. The good news is that when I saved (exported) the project, there WAS no freezing. I know I could get the extra drive, as someone suggested, inside my computer, but if I were to buy another computer, what specs would you suggest on a Windows computer?
Make sure your hard drive has lots of space. 1 TB is pretty standard now.
Remember that desktops are built for power and laptops are built for portability, so you always get better performance from a desktop. But if your processor is fast enough, you've got a good RAM load (12-16 gig is a good level) and you've got lots of free space on your hard drive, you should be fine with either.
But also remember that a lot also depends on the format and codec of video you're editing how editable it is. I'm concerned that you're getting freezing with an i7. I don't know where your video is coming from or what format it is, but if it's giving an i7 problems, you may find instability issues even with a faster machine.
There is a class of computers for people who are devoted to video games. I've never played a video game but bought a "gaming" laptop made by ASUS several years ago. It has worked well for video editing, including 4K.