I am looking for software to design a fantasy map. I am aware that there are several specific software for Windows that does that; however, I am more interested to create a massive (think about 40Mpx height by 50Mpx width) image,and I prefer to be done in vector (as in SVG). I can make with raster (BMP, PNG, etc) as well. It is important for me to work on extremely small detailed parts of it (so big zooming factors), but I care about performance (in the sense that I'd like to be able to zoom in and out without having to waste minutes waiting for a load) but I'll settle for less.
I would be happy to find some kind of software that would generate a grid of smaller images (sort of like Google Maps is implemented) such that I can edit the smaller images and view the larger thing once fully zoomed out.
Currently, I use Windows 10 and OSX v.10.12 and my computer can run some of the more demanding 3D games released that was in 2017 (so really I'm looking for software that won't waste ram on extensive UI and functionality, ahem, Photoshop/Illustrator; using these would basically be using a drill on a nail, which I don't normally mind, except that when the image is this big you really want to minimize memory waste).