drmike: Well first step would be some details as to what is occurring.....
Are you downloading via GoG Galaxy? The old GoG Downloader?
OS? Windows 10? iOS? Pants around belly button Linux?
What is your provider?
DO you have anything else running n the background?
What speeds are you getting?
Firewall?
etc....
Friendly reminder that only you can see what is occurring. All we can do is make guesses if we don;t have anything to go on.
edit: Also this would be a good start:
https://www.google.com/search?q=gog+slow+download Win7, I'm using both gog galaxy and classic way, I get 1 MB speed give or take, I don't know do I have firewall active, but I only have Avast running.
I'm in Europe, so provider info won't really help.