Studio Display XDR + M5 Pro MBP : scrolling stutters at 120Hz

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Studio Display XDR + M5 Pro MBP : scrolling stutters at 120Hz

I'm running into an issue with my new MacBook Pro M5 Pro (14" 18 CPU /20 GPU - 48GB) hooked up to a Studio Display XDR and wanted to see if anyone else is seeing this.

UI scrolling across all apps is noticeably choppy when the XDR is set to 120Hz or Adaptive (47–120Hz), especially during web browsing. The MacBook’s internal screen is smooth, and the stutter happens whether the MacBook lid is open or closed in clamshell mode.

Details on my setup:

- macOS 26.2.2 (latest)

- XDR firmware 26.4, connected directly via the supplied Apple Thunderbolt cable (already tried power cycling).

- Happens with both the internal trackpad and an MX Master 4.

- Tested the exact same XDR setup with a base M5 and an M5 Max: both were smooth at 120Hz. Seems oddly specific to the M5 Pro chip.

- Tested with a second (work) MBP M5 Pro and reproduced the exact same stuttering behavior, pointing to the M5 Pro chip variant.

- Choppy with Safari and Chrome browser.

Is this a known macOS display driver bug on the Pro chip ?

MacBook Pro 14″, macOS 26.6

Posted on Aug 31, 2026 10:55 AM

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Answer 1

Top-ranking reply

fboss Author

Level 1

26 points

Sep 2, 2026 8:55 AM in response to fboss

parse_surfaces.py

There is a way to illustrate the issue by capturing traces with Xcode Instruments

About 30% of the frames at 120hz are either dropped or repeated. MacBook M5 Pro connected to the Studio Display XDR. Results confirmed with another MacBook M5 Pro.

1) set the display to 120hz or 60hz

2) xcrun xctrace record --template 'Metal System Trace' --time-limit 30s --output  stutter_120hz.trace --all-processes

3) scroll a long web page or document for ~30 seconds

4) xcrun xctrace export --input stutter_120hz.trace --xpath '/trace-toc/run[@number="1"]/data/table[@schema="displayed-surfaces-interval"]' --output surfaces_120hz.xml

5) python3 ./parse_surfaces.py surfaces_120hz.xml (see script attached)

at 120hz :

Total frames: 2562

Held for exactly 1 interval (healthy): 1794 (70.0%)

Held for exactly 2x interval (dropped/repeated): 694 (27.1%)

Held 3x+ longer (multi-frame stalls): 74 (2.9%)

Longest single stall: 991.7 ms

at 60hz:

Total frames: 1717

Held for exactly 1 interval (healthy): 1676 (97.6%)

Held for exactly 2x interval (dropped/repeated): 20 (1.2%)

Held 3x+ longer (multi-frame stalls): 21 (1.2%)

Longest single stall: 383.3 ms

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Answer 2

Aug 31, 2026 1:17 PM in response to fboss

some issues with new 5K Studio Display and 5K XDR display have been reported here on the forums.

The most egregious is that MacOS assigns TWO display generators (an un-necessary 'trick' developed to support the 6K XDR display) to support these displays in some instances (and we have not been able to determine exactly WHAT instances.) This means Left and Right halves of the display are supplied data separately. sometimes this causes crashes, where the Crashes look like this:

You appear to have more information, and more specific information, from your recent experiments across several models of recent Macs at your fingertips.

>> Won't you please contact Apple Support, and ask to add this new information to the existing Bug Report(s)?

Doing so may clarify the issue enough for a more rapid solution, which has NOT been forthcoming at this writing.

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Answer 3

fboss Author

Level 1

26 points

Sep 7, 2026 10:30 AM in response to fboss

The MacBook Pro is powered by the Studio Display XDR, with Energy Mode set to High Power. But powermetrics shows the GPU remains at a low 338–393 MHz clock during 5K/120 Hz scrolling.

As a workaround, a small app was written to schedule short Metal workloads to keep the GPU active. This increases the healthy frames from approximately 70% to 98% and makes the scrolling as smooth as it should be.

This strongly suggests that the GPU Dynamic Voltage and Frequency Scaling (DVFS) on the M5 Pro is overly conservative. The issue may also affect the new Mac mini with the M5 Pro.

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Answer 4

Sep 1, 2026 1:57 PM in response to fboss

<< In my case, the issue occurs in clamshell mode with the lid closed, when using only one external display. <<

That does not seem to keep MacOS, under certain conditions as yet not fully decoded, from assigning TWO display generators to that one display.

It seems incredible. It's wonky, but that appears to be at the heart of this cluster of issues.

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Answer 5

Sep 1, 2026 1:40 PM in response to fboss

That illustration is from the closely-related case where the Mac assigns two display generators AND under certain circumstances, especially adaptive sync, they get out of sync and cause a kernel panic.

I included it to illustrate in a very visceral way that the two display generators issue really does divide the screen into Left and Right halves, updated separately. (Some users have been incredulous that was possible all, and refused to believe it would self-configure that way.)

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