Update, November 11: With Dishonored 2‘s Steam rating down to 54 percent, Bethesda’s finally got around to acknowledging there maaaay be some issues, and a patch is on its way soon.
From the official update:
“We have been monitoring the PC forums and social channels and while we’re excited to hear that many of you are enjoying the game, we are disheartened that some of you are experiencing PC performance issues on some systems. We are actively working to provide an update to address your concerns. The patch and its release notes will be available in the coming days.”