The changes from WT-3705/PR 3765 had a very noticeable impact on performance. There are a number of Jenkins performance tests that are showing 10-25% degradation. Two such examples are medium btree Load Time and medium btree Read Throughput. I have attached their plots. There are a significant number of other jobs as well.

The load time increased by 23% and the read throughput plot shows a drop of almost 13%.