Played around with the settings a bit more. Hardware cursor on makes the mouse sensitivity settings disappear now, so I needed to disable that, set the sensitivity, then re-enable it. No wonder I couldn't find it earlier!
If I remember right, before the last two updates I had vsync disabled and framerate set to unlimited in game, and 1/2 refresh rate forced in Nvidia Inspector (to lock it to 30) but this makes the camera judder and feel a bit unresponsive now. If I set the framerate limiter to 30, along with 1/2 refresh rate, it feels smoother. Might be better still if I try limiting the framerate in Nvidia Inspector instead. So I guess you could try changing the various settings for framerate/vsync and see if there are any improvements.