Ah, currently, I'm running FreeBSD 11.1, running Kibana 5.3.0. Copy of the last few lines of /var/log/kibana.log :
{"type":"log","@timestamp":"2017-08-26T18:37:06Z","tags":["info","optimize"],"pid":17473,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T18:37:16Z","tags":["info","optimize"],"pid":28593,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T18:38:25Z","tags":["info","optimize"],"pid":56413,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T18:38:41Z","tags":["info","optimize"],"pid":68214,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T18:42:45Z","tags":["info","optimize"],"pid":16907,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T18:43:01Z","tags":["info","optimize"],"pid":33850,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T20:52:57Z","tags":["info","optimize"],"pid":30448,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T21:02:07Z","tags":["info","optimize"],"pid":68507,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-26T21:27:19Z","tags":["info","optimize"],"pid":37410,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T16:59:29Z","tags":["info","optimize"],"pid":78511,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T19:53:27Z","tags":["info","optimize"],"pid":51287,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:07:12Z","tags":["info","optimize"],"pid":21963,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:07:39Z","tags":["info","optimize"],"pid":37926,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:07:56Z","tags":["info","optimize"],"pid":51410,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:08:24Z","tags":["info","optimize"],"pid":69149,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:08:42Z","tags":["info","optimize"],"pid":87011,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-27T20:09:27Z","tags":["info","optimize"],"pid":3585,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
{"type":"log","@timestamp":"2017-08-30T13:14:39Z","tags":["info","optimize"],"pid":15257,"message":"Optimizing and caching bundles for kibana, timelion and status_page. This may take a few minutes"}
Any other information needed, please feel free to ask.