So I picked up a reasonably good server at 4CPU and 16GB RAM. At the rate at which the posts are getting migrated, it will take me 9 days for just the posts to get migrated. The users took 2.5 hours to get migrated. Safe to say that this is going to be a no go for me as is but at least I can spend some months familiarizing myself till I figure out a solution for this bulk migration.
PS:
In the migration script I see that duplicate emails are not imported. What are the different ways that duplicate is determined? I noticed that xyz@gmail.com is treated same as xyz+1@gmail.com and xy.z@gmail.com
Is there any other pattern as well.