Remedy has addressed Quantum Break (opens in new tab)'s less than auspicious launch on Windows. It was surprising that a company with history on PC should turn out a substandard port (opens in new tab), but fixes are in progress.
Chief among them is collaborating with AMD and Nvidia on an overall performance boost. There are also rare cases of video memory becoming fragmented after long play sessions, resulting in slow rendering. They're under investigation for now, but restarting the game will resolve the issue in the interim. For best results at present, Remedy recommends AMD Radeon drivers 16.4.1 (opens in new tab) and Nvidia GeForce drivers 362.00 (opens in new tab).
If you suffer from stuttering, you'll be relieved to hear Remedy has it figured out: "a major rounding error introduced into our refresh rate predictions on shipping". A patch will arrive in the near future, as will the addition of a 'quit' option—always useful—and direct control over settings like film grain.
The full breakdown (opens in new tab) also confirms suspicions about how Quantum Break is rendered—it's not native 1080p. À la Xbox One, images are constructed from four buffer images rendered at two-thirds of the chosen resolution with 4xMSAA. "Engine assigns input geometry samples from 4xMSAA rendering into shaded clusters in order to maximize covered geometry while keeping the performance on acceptable level by reducing expensive shaded samples." In other words, it's permanent. On the other hand, the framerate lock will disappear in May when Microsoft allows developers to disable vsync.