Some requests show latencies of more than 10 seconds when running a long workload (~5 million updates) with the stable timestamp pinned.

I reran the test workload from PM-1844 on 4.4.4-rc0 to see how it performs with the fix for WT-6924. The test workload has a long "grow" phase, which performs a lot of updates (with a few inserts and deletes) designed to grow the WT history store.  Before the fix for WT-6924, this phase cause the WT cache to vastly exceed its configured size limits which also caused many updates to have high latencies.  

In this test, the WT cache adheres to its configured size, and update throughput looks more consistent through much of the test.  But by the end of the test we are still seeing much lower performance and some individual operations (~9000) have latencies > 1 second.

I'll attach data.tgz with the FTDC data and mongod log file.