Memoize topic-partition forget secs. in MessageReader
Attempt to use a normal Properties object for config.

Let’s see if this makes any difference.
Remove rate limiting

DIE DIE DIE.
Periodically check if we need to upload logs

Uploader#applyPolicy() is a real performance killer as it talks to ZK
a lot, and previously it was invoked after every single message
processed. Should probably extract the “delay” to a config. parameter,
but for now this is OK.