I'm UK on VM's Vivid 200 Gamer so similar specs to you. I have several Macs that were really slow to backup or restore files. I decided to backup the Macs to a Synology NAS and run the IDrive NAS client. The difference between the Mac client and the NAS client was night and day - the Synology IDrive client smokes my connection when uploading files and is fast for restores but I can't remember the actual speed, certainly not 200Mbps!
There must be some sloppy programming in the Mac client that slows it down; haven't tried the Windows client.