Currently X-Analytics data is passed from Varnish to Hadoop via HTTP headers. Those headers are then passed to clients, which sends pointless data to end users.
Instead of relying on headers, this data could be passed by Varnish via VCL_Log, which lets it pass data to the backend without exposing headers to the client.
This would reduce our outbound bandwidth and the amount of useless data in the first TCP packet the client received, leaving more room for actual content actionable by the web browser.