Batman: Arkham Knight [official site] returned to sale in October, after months of work fixing the poor performance that saw it pulled from sale. It was still wonky. That's a shame, becase it's a pretty good game according to our Adam. Work still continues, and this week has brought another patch which fixes more things but, apparently, still has issues.
Pore over the patch notes and you'll find bug fixes big and small, as well as encouraging notes like "Improved VRAM management to reduce framerate hitches".
Scroll down to the comments on those notes, though, and you'll find some folks saying this patch finally fixes the game for them, but also some complaining that it had been playable for them before but this update turned it all stuttery. That Eurogamer lot whipped their calculators, multimeters, oscilloscopes, and scanning electron microscopes and drew the conclusion that yep, it's still wonky.
Maybe it'll always be wonky. I wonder when they'll declare it 'done enough'. They've already given up on multi-GPU support.
Publishers Warner Bros. are offering refunds on Arkham Knight until the end of the year, regardless of how much you've played it.