Increase in rebalance time for eventing rebalance by 3x

Seeing 3x Increase in eventing rebalance times (this is a curl function example, but it is seen in normal bucket op rebalance tests as well) . Possible duplicate of MB-45364, but filing just in case.

4813 - http://perf.jenkins.couchbase.com/job/themis/9590/ - 91s

4678 - http://perf.jenkins.couchbase.com/job/themis/9343/  - 31s

Logs : 

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-themis-9590/172.23.96.16.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-themis-9590/172.23.96.17.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-themis-9590/172.23.96.20.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-themis-9590/172.23.96.23.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-themis-9590/172.23.97.177.zip - Eventing node

Stats Comparison : http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=themis_700-4813_execute_handler_9411&snapshot=themis_700-4678_execute_handler_c5cf 

Changelog : here