I'm working with extremely large illustrator files on a MacBook Pro 2015. Now I'm looking for a setup that will make life smoother for me. 

I need to know what's most important – fast CPU or GPU?

Would it get a lot faster if I for instance install an [external GPU](https://bizon-tech.com/us/bizonbox2-egpu.html/) to my Macbook Pro or should I forget Mac and go for a Windows computer?

I mean since Illustator still(!) only uses one core from the CPU I guess it's all about gigahertz when it comes to CPU?

A lot of questions in one post here but the main issue is: how should I think when it comes to make Illustrator fast?

**Edit:** I should perhaps add my current config:
Macbook Pro 2015, 2,5 GHz Intel Core i7 with NVIDIA GeForce GT 750M 2048 MB and 16 GB 1600 MHz DDR3

Also I should note that when working with my documents Illustrator runs at 100% of CPU constantly. 100% as in one out of four cores.

**Update oct 2017:** I have now tested my document on a Windows computer with one of the fastest desktop processors out there right now, the i7 4.0 Ghz and it wasn't that much faster to be honest. Next up will be testing with a computer that has a major GPU.