For a file that large, I would break it down by main lines. For example, my four main surname lines would be Barnett, Carey, Trammell, and Wrenn. Then I would upload each file probably a week apart so I could connect them properly to myself and to check for matches. I don't have that many names, but when I did my gedcome file I skipped a number of large collateral lines. I had connect with several researchers and they had provided lots of information that I entered, but didn't think it was essential to add at the present time to WikiTree.