Update perf test

[caleblloyd]

Added some parallelism to the perf tests

Stage             Operations Data (MiB) Duration (s)   P50 (ms)   P95 (ms)   P99 (ms)
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Insert                20,000       2.44         0.60       0.42       2.52       8.20
Get                   20,000       2.44         0.45       0.36       1.26       2.56
Update                20,000       2.44         0.49       0.38       2.14       4.94
Get (refresh)         20,000       2.44         0.96       0.75       2.46       5.54
Delete                20,000       2.44         0.44       0.34       1.98       4.25
-------------------------------------------------------------------------------------
Total                100,000      12.21         2.94                                 
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