Go-XDCR: No improvement in replication speed when nozzles and batch size are increased

Case 1
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No filter, default replication spec
Arunas-MacBook-Pro:sherlock apiravi$ curl -X POST http://localhost:12100/controller/createReplication -d fromBucket=default -d uuid=localhost:9000 -d toBucket=target -d filterName=filter2

Replication rate : 1.5K - 2K ops/sec

Case 2
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No filter, xdcrWorkerBatchSize=2000 xdcrSourceNozzlePerNode=4 xdcrTargetNozzlePerNode=10

Arunas-MacBook-Pro:sherlock apiravi$ curl -X POST http://localhost:12100/controller/createReplication -d fromBucket=default -d uuid=localhost:9000 -d toBucket=target -d filterName=filter2 -d xdcrWorkerBatchSize=4000 -d xdcrSourceNozzlePerNode=4 -d xdcrTargetNozzlePerNode=10

Replication rate : 1.5K - 2K ops/sec

Case 3
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No filter, xdcrSourceNozzlePerNode=4 xdcrTargetNozzlePerNode=10
Arunas-MacBook-Pro:sherlock apiravi$ curl -X POST http://localhost:12100/controller/createReplication -d fromBucket=default -d uuid=localhost:9000 -d toBucket=target -d filterName=filter2 -d xdcrSourceNozzlePerNode=4 -d xdcrTargetNozzlePerNode=10

Replication rate : 1.5K - 2K ops/sec

Pls see screenshots attached.