The read throughput in the 50R/50U (and the readonly test) of the wiredtiger-perf-long-job Jenkins job is showing about a 10% degradation recently. That is tests 2 and 4. Interestingly enough the 80R/20U job does not show a degradation.

The loss started with this build: http://build.wiredtiger.com:8080/job/wiredtiger-perf-long/247/
and has been consistently lower since that build.

There are several merges included in that build.