[py-tpcc] drop in throughput between 6.0.3 and 6.5.0

6.0.3 build tested : 6.0.3-2885
6.5.0 build tested : 6.5.0-4380

The summary of results of the py-tpcc script shows some drop in throughput when run against 6.5.0 vs 6.0.3

Result summary from 6.0.3-2885
Execution Results after 3600 seconds
------------------------------------------------------------------
Executed Time (µs) Rate
DELIVERY 6634 17989486647.1 0.37 txn/s
NEW_ORDER 76134 73444134837.4 1.04 txn/s
ORDER_STATUS 6641 660233349.562 10.06 txn/s
PAYMENT 71978 13137749547.0 5.48 txn/s

Result summary from 6.5.0-4380
Execution Results after 3600 seconds
------------------------------------------------------------------
Executed Time (µs) Rate
DELIVERY 6424 19397239022.7 0.33 txn/s (-8.5%)
NEW_ORDER 68670 70670955712.6 0.97 txn/s (-7%)
ORDER_STATUS 6193 741795059.919 8.35 txn/s (-17%)
PAYMENT 65368 13217099903.6 4.95 txn/s (-9.7%)

Jobs
6.0.3 : http://qa.sc.couchbase.com/job/cen006-ps-n1ql-vset00-00-tpcc/120/console
6.5.0 : http://qa.sc.couchbase.com/job/cen006-ps-n1ql-vset00-00-tpcc/121/console