Uh, that is a deep drop. Just thinking, could it be related to this: https://github.com/Kong/kong/commit/de4a002565a1723bff9014cb...
Definitely something for us to investigate! Thank you for feedback (I'll collect this information to our backlog).
Last August, I tested the Dropwizard service with this setup which recorded about 20,000 RPM on GKE. This year, the same setup sent about 4,000 RPM to the Dropwizard service and the http-log plugin sent only about 200 RPM to the other service.