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JSON is a machine-readable format, so there is no need to generate statschannel output in a "pretty" form. Quick experiments show that redundant whitespace adds up to about 40% of the JSON payload produced by statschannel code.

Yes, lib/isc/httpd.c supports DEFLATE compression via zlib and that enables massive savings in terms of payload size, but it requires clients to send the Accept-Encoding: deflate HTTP header in order to kick in, so IMHO HTTP-level compression and producing "minified" JSON data are tangential mechanisms rather than exclusive alternatives.

Piping "minified" JSON through jq allows one to get the "pretty" form without the extra bandwidth cost.

Some semi-random measurements:

• v9.19, 4 logical CPU cores

  $ curl -s http://localhost:8080/json | wc -c
  71386
  $ curl -s http://localhost:8080/json | jq -c | wc -c
  41881
  $ curl -s -H "Accept-Encoding: deflate" http://localhost:8080/json | wc -c
  4150

• v9.19, 32 logical CPU cores

  $ curl -s http://localhost:8080/json | wc -c
  391217
  $ curl -s http://localhost:8080/json | jq -c | wc -c
  227837
  $ curl -s -H "Accept-Encoding: deflate" http://localhost:8080/json | wc -c
  16721

• v9.16, 4 logical CPU cores

  $ curl -s http://localhost:8080/json | wc -c
  896972
  $ curl -s http://localhost:8080/json | jq -c | wc -c
  529643
  $ curl -s -H "Accept-Encoding: deflate" http://localhost:8080/json | wc -c
  25880

• v9.16, 32 logical CPU cores

  $ curl -s http://localhost:8080/json | wc -c
  6954362
  $ curl -s http://localhost:8080/json | jq -c | wc -c
  4106064
  $ curl -s -H "Accept-Encoding: deflate" http://localhost:8080/json | wc -c
  174557