The beta phase for Call of Duty: Modern Warfare 4 has started, facing performance issues, especially for PC gamers who report input delays with mouse and keyboard setups and a perception that multiplayer favors controller users due to aim assist. Activision and Infinity Ward are working to improve the PC experience, focusing on customizable settings, mouse input responsiveness, and a preload feature for shaders. Some players are frustrated with the game's requirements for Secure Boot and TPM 2.0, which may not be recognized even after installation. An update is planned to address footstep audio, map voting, weapon balance, and bug fixes. The beta currently has a 53% positive rating on Steam, with concerns about movement mechanics and map sizes affecting gameplay.