I think David's right. 220 images converted to JPEG full size will be pretty big. I just exported one of my 12mp NEFs as a full-size JPEG and it's 11MB. Your D600 file should be twice that or thereabouts, call it 20MB. You are attempting to upload 4.4GB, which is quite a lot. Most internet users in the US have about 1 Mbit uplink speeds if they are on typical cable modem / DSL / etc lines. At those speeds, you're looking at ten hours - assuming that they don't throttle you, and there are no interruptions. (Your D300 would be only half as bad, incidentally.)
For comparison, typical wireless networks in homes are 54Mbit or 144Mbit.
I don't think you have a problem at all, actually!
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!