@mksavic There was a lot of issues that were fixed in the logstash beats input related to connection management; I think we should try to update the beats input plugin first and see if it fix your problem.
You can update the plugin using the following command:
bin/logstash-plugin update logstash-input-beats
Also, I think you should look at Logstash 6.3; there was a log of performance improvements that were done between 6.0 and 6.3.