The current setting for memory_page_max in WiredTiger collections is 100MB. This helped with throughput on insert heavy workloads.
We have recently made enhancements to WiredTiger to lessen the benefit of a large memory_page_max setting. We should consider switching to the default setting (5MB).
There are cases where an application thread writes a page to disk after it reaches the memory_page_max setting - having this value large can cause operations to experience high latency.
I've run a few workloads locally and see equivalent performance with a smaller memory_page_max, and generally significantly smaller values in the profiling of slow operations.