While looking into performance issues in one of our clusters I've noticed that the v4.17 Java driver does uses some sub-optimal queries on connecting to the cluster:

Both of these queries force full table scan as there's no key reference. I've tried appending WHERE key = 'local' to these queries and as a result the Session creation got about 90 % faster in the troubled cluster case. (YMMV)

This seems to be fixed in the 3.x version of the driver.

Looks related to this issue.