Hello,
I am experiencing the same problem with large file (50GB+, bluray disc converted to iso file) copy action towards my 3TB drive (Hitachi HDS5C3030ALA630). Copying from the 3TB drive towards other drives ( 2GB, 3TB (2x 1.5TB in Raid0)) works fine.
I think I could Zip or Rar or Split the big file into smaller parts (multi volume) which will fit into memory (I have 8GB RAM) and copy the smaller parts to the big 3TB drive, but that would be cumbersome. I don't really want to do that every time.
So I experience the same issue while copying towards the 3TB drive, Windows Task Manager shows my RAM usage is going towards 99% and then everything is slow, though mouse cursor movement is working fine, Task Manager shows very little CPU usage, but every click on any window is slowed down or not even working. I have tried fixed pagefile size, automatic, it all doesn't seem to help.
The only thing that is different is that my 3TB drive is a GPT volume. I have no knowledge if that could affect the copy behaviour though.