Download NvidiaInspector, open nvidiaProfileInspector.exe and choose F1 2016 from the drop-down menu.
Under 2 - Sync and Refresh, Change Vertical Sync to Force on
& Vertical Sync Tear Control to Adaptive.
Apply changes.
This should prevent the FPS from dropping excessively during cut-scenes / flashback. Make sure you have the latest Nvidia drivers installed before doing this.