Hello @Sorin_GFS, Welcome again to the MongoDB community forum,
I have tested the connection and a find query in each version (4.3.0, 4.6.0, 4.12.0) of the node-mongodb-native and same configuration as yours, I did not found any performance issues in connection or a find query.
You can check and execute the same code from the GitHub repository,
I checked there are no major updates specific in DB connection from the 4.3.0 to 4.12.0 versions, you can also check in the release notes:
Secondly, there are many possibilities why it is taking more execution time that is not related to node-mongodb-native driver, check the similar question that may help you,
Thanks.