I've been writing a paper for an evening course I've been taking, related to chess engine searches.
To get a clean output of the search I had to turn off most of the features, like killer moves, PVS search, aspiration windows etc.
Funny thing, when I was going to turn off the futility pruning, I noticed it was already turned off... :) I apparently accidentally returned false for "use futility pruning" even when it met the requirements.
That means Mediocre v0.4 is playing without it.
I ran a quick 128 game test and turning it on seems to gain some 30-40 elo points in self play. Not too huge, but definitely silly to not have.
I'll be sure to turn it on again in the next release. :)