We recently upgraded our nodejs application in production from mongodb driver version 3.3.3 to 3.5.2.

After the upgrade we detected a performance impact in the application. Mongo Server is a ReplicaSet in Mongo Atlas (M30 Tier, 3 members replica set).

The driver connect options is the following:

{
            useNewUrlParser: true,
            useUnifiedTopology: true,
            ignoreUndefined: true,
            connectTimeoutMS: 60000
 }

We have no deprecation or other warning from the driver logged from the Application.

This is the document metrics from Mongo Atlas where you can observe the major increase in operation throuput after reverting back to 3.3.3 driver version:

One weird fact is that the same application is running in other production environment with a very similar setup, but the Mongo Server is a PSA (Primary Secondary Arbiter) without SSL connection. In this env we haven't experienced any performance issue.

The same issue happens in version 3.5.0.