Update 4: 2K Games has finally posted an official statement on the matter:
We know how important having options that best suit your PC’s performance capabilities are. The team has been hard at work ensuring that Mafia III’s performance is consistent across all platforms, and right now the game runs at a solid 30 frames-per-second. We are currently working on an update for PC that will give players the option to play Mafia III at higher framerates. We’ll share more details about the update, and when you can expect it to arrive, very soon. In the meantime, the team welcomes feedback and would like to hear from you about what performance adjustment options are important to you. We’re actively considering a number of additional post-launch improvements on PC that would give players more control over how they can tailor the game’s experience to suit their rig’s performance. It’s been an incredible journey developing Mafia III and we couldn’t be more excited to get the game in your hands and hear what you think!
Update 3: Popular media personality John Bain (also known as Total Biscuit) tweeted that 2K has been in contact with him, and confirmed that the current builds of Mafia 3 are locked to 30 fps on PC. The same 2K contact promised improvements (without giving a specific date) and said that the company will issue a statement soon.
I have had confirmation from 2K that the current builds of Mafia 3 are locked to 30fps on PC. They claim improvements "soon" and statement.
— John Bain (@Totalbiscuit) October 6, 2016
Update 2: It seems that Mafia 3‘s game logic is tied to the framerate, so the 30 fps cap isn’t a bug (and attempts to remove the cap may introduce issues such as the game running too fast) Source: NeoGaf
Update: PC Gamer reports that the game is indeed locked to 30 fps on PC.
According to Twitch streamer CohhCarnage, the PC version of the highly anticipated Mafia 3 may be locked to 30 fps. CohhCarnage says that he talked to a Hangar 13 employee about the framerate lock and the developer seemed surprised, so there is a chance that this is just a bug with the pre-release version of the game and not something done on purpose.
Mafia 3 is out tomorrow. The game’s official system requirements don’t seem so high, so it would be a surprise if the game is indeed locked at 30 fps on PC.