The January 8 SteamOS beta update introduces a feature called ntsync, which provides kernel-level support for a driver that enhances Windows game performance on Linux systems, particularly for the Steam Deck. This update may improve performance for older titles in the Call of Duty franchise and other classic games. Testing on Call of Duty 4: Modern Warfare showed minor frame rate improvements when using the ntsync-enabled Proton-GE fork, stabilizing frame rates around 135-144 FPS compared to 130-140 FPS on the fsync build. Users have reported that issues like framerate drops and graphical glitches in Call of Duty Black Ops have been resolved with the new Proton-GE/ntsync combination. To utilize these improvements, users can opt into the SteamOS 3.7.20 beta branch and install the latest Proton-GE version via the Proton Up-Qt app.