Thank you @stevenmatison appreciate the pointers provided.   We are not using conventional nginx as load-balancer but instead have BigIP F5. And after examining configuration there we have identified connection limit parameter which was the culprit. We have updated it and this has made some difference in the user experience.    We are looking to increase the number of Hue and HS2 instances in the cluster to boost the overall and query performance.   Many thanks.  ... View more