Yes, this can be quite normal. FTP is not a very nice protocol, and there is lots of going backwards and forwards for each file - and this latency can add up very quickly.
Downloading via a ZIP file is way more efficient because it can optimise the transfer for a single big data block, and it can also compress the data. You have not specified the data, but I would guess that the data is very compressible.
180k files @75k each is 13.5 gigs of data. At 3 MB per second (which sounds suspect, ISP's typically quote megabits, not megabytes), without compression, this would take 1 to 1.5 hours to actually transfer the data. If the speed is 3 megabits, the time would be 10-15 hours... and this excludes the latency which would be a very big factor. You have not advised the latency between the sites, but lets say its 10ms round trip (which would be on the low end - you would be looking at a, at least an additional 30 minutes. I imagine in reality you would be looking at an extra 2-4 hours).