We did some benchmarks before upgrading from the 2.13.2 to 3.2.1 and we noticed an important performance gap between the 2.
For writing 1 Million documents we noticed a gap of around 5% in favor of the 2.13.2 driver (Using the old com.mongodb.BasicDBObject API or the new CRUD API that uses org.bson.Document).
For reading 10 Million documents we noticed a even bigger gap of around 143% using the old API and around 50% for the new API, always in favor of the 2.13.2 driver.
What do you think of the benchmarks and do you have your own benchmarks ? Or maybe best practices for the New API.