On the new M5 Pro platform running macOS, UI animations (window dragging, Safari/Chrome scrolling, Mission Control) on an external 5K 165Hz display appear to render at a much lower frame rate (~60Hz) or exhibit severe micro-stuttering. However, the mouse cursor and desktop wallpaper dragging remain perfectly fluid at 165Hz, indicating a potential issue in the WindowServer compositor or display pipeline rather than the physical link.
Environment
• Hardware: MacBook Pro (M5 Pro) • OS: macOS 27.0 beta 3 (26A5378j) • External Display: 5K 165Hz monitor connected via DisplayPort (DSC confirmed via IORegistry). System Settings correctly detects and selects 165Hz.
Expected Behavior
All UI elements, including window movement, application scrolling, and system animations, should render smoothly at the native 165Hz refresh rate matching the hardware capabilities.
Actual Behavior
The display output appears split between two different refresh rates: 1. Full 165Hz: The hardware mouse cursor and desktop dragging (empty area selection) are perfectly smooth. 2. ~60Hz / Jitter: Application windows (Finder, Safari, Chrome) stutter heavily when dragged or scrolled. Mission Control animations suffer from micro-stutters. Note: This specific combination suggests the Hardware Cursor layer is running at full rate, but the WindowServer compositor layer is throttled or dropping frames.
Troubleshooting Performed (No Change)
• Verified with multiple certified DisplayPort cables. • Tested across various resolutions (Scaled/HiDPI modes) and toggling DSC. • Regression Check: This issue did not occur on a 4K 144Hz HDR monitor previously, and initial community feedback shows other M5 Pro users experiencing this specific 165Hz window-dragging jitter, while M4 Pro / base M5 users on the same macOS beta do not seem impacted.
Questions & Diagnostics
1. Is this a known regression related to the new M5 Pro display engine / Display Coprocessor (DCP) pipeline handling 5K high-refresh-rate timings?
2. Are there specific defaults write commands, Quartz Debug profiles, or custom logging arguments (WindowServer, DCP, or Metal) we can enable to capture frame presentation metrics?
I have captured a sysdiagnose, IORegistry dump, and high-frame-rate screen recordings, and am ready to attach them as soon as this feedback is processed.
Case / Feedback Reference Feedback ID: FB23616959 (Captured after the system format)