Mongodb > 3.0.0 Import data is extremely slow

  mongodb, question

After exporting with mongodump, v3.x is slower than v2.6.6 mongorestore by more than one order of magnitude. about 2 million data (2GB) takes only 5 minutes in total. v3.x does not know if it is only 3MB/S imported due to authentication

I imported more than 300 g of data for two days before importing hundreds of m.