MongoDB supports bulk insert http://docs.mongodb.org/manual/core/bulk-inserts/
I have tried it in Meteor collection:
Orders.insert([ { \"cust_id\
You could use rawCollection which is node mongodb driver implemetation in Meteor.Collection.
await Orders.rawCollection().insertMany(arrOfOrders)
It works on 70M data in my case. (await makes it synced so you should consider to use it or not for your purpose.)