You can selectively copy, that will be a lot faster. I just didn't want to complicate things if you didn't know what you were doing

Once you copy the files and install the symlink stuff, go into the master folder, rightclick on the folder you want to symlink. you will see "Pick Symlink Source" in the menu. Go to the slave folder, right-click an empty spot and select "Drop as... > Symbiolic Link". Then do that again for the next folder and any other files you'd want to link. You can only do one at a time.