I had a prevoius post in "Kibana eating up Chrome" and would like to link to this post, but it does not seem possible.
We found out by analyzing the issue in Kibana 6.2.1 that the layered donut could be the origin of the problem. Whenever we build a 3 og 4 lyered donut ob just a very small dataset, the webapp uses unreasonable amount of processor and ram. With a little more data than the appr. 2K documents, the webapp stops responding.