Data Gateway TCP security

The documentation says that the Azure Datagateway transmits data from on prem to Azure with "Direct TCP".  There is a note that it can be configured to use HTTPS, but that this will significantly impair performance.

Does this mean that by default the TCP data transmission is unencrypted and thus insecure?

https://powerbi.microsoft.com/en-us/documentation/powerbi-gateway-onprem-indepth/

Thanks,

David.