The automated performance testing on Windows has shown a performance change correlated with a recent update of WiredTiger into MongoDB master branch.
The job showing the change is:
The particular build that triggered the change is:
Which included https://github.com/mongodb/mongo/commit/c91b93d2786342505fd9e151c8aa6b68ee03a1fb for the first time.
It was the small documents job that shows a regression, the standard and large document workloads don't show a performance change. All small document runs are slower.