Mostly visible on 2n-dnv [0]. Does not seem to affect the -rnd version of the suite.
It seems not only average is decreased, but also stdev.
The task is to find the causing commit.

[0] http://csit.fd.io/trending/#eNp1kN0KgzAMhZ-m3kigRtTdeDHne4zOZlP8WWk7mXv6VRCijF0koXyHc5I6_7R0dTSUIqtEUQksOh2aSM9xGLMxgBPoaYZEPghN8s6yFLTRPXQmh-J0g6QB8u36CuUaNRDKHkZrVxu8rDb65Q-eTEy7MPmTxGplSbE8xDHy5HYZvwux8m7VSK77EMvDGcyb8COMkuaY4Rezo9uVRS2yOnJeWV-iRASJgBhLGWRbi2jSG8sB0wP7AvWJZsg