I’m looking at buying some computer parts and was wondering what would provide the largest benefit to compiling to neko/C++, do I need CPU speed, hard drive speed, more ram? Any insight is appreciated.
Have a minimum amount of RAM (8 GB+ is pretty standard nowadays) and try and put your source files on an SSD to speed up file access (as compilers need to access a lot of files). Fundamentally, after disk access, compile speed is going to amount raw CPU work. That means that a faster processor with more cores will make a bigger difference.
Linux also compiles faster than Windows, generally, for what that’s worth 
I got a Linux machine with plenty of RAM and a decent CPU, and it really does speed things up. But I’m comparing against an 8-year-old laptop, so that isn’t saying much.
Nowadays it should be pretty standard, but make sure you have a SSD. That’s the biggest performance boost ( in general ) you can get for any machine.