Most excitingly, apart from GPU optimisation, is the inclusion of the very long lists of fixes already implemented for console versions, such as the adjustment of various sound volumes and knife lunge distance. JD_2020 says the reason this has taken so long is because "the issues we've addressed to-date on the PC took higher priority over the other fixes the consoles received that the PC hasn't yet."
We are promised an up-to-date "in progress" list of fixes tomorrow, so stay tuned for that information.