User profile for user: Hiramasadon
Hiramasadon Author
User level: Level 1
4 points

Keynote issues on MacBook Neo with 4K extended display

I purchased this Mac primarily as a dedicated machine for Keynote, but I'm experiencing serious performance issues whenever I connect a 4K external monitor as an extended display.

The cursor movement on the external monitor becomes noticeably sluggish. When using Keynote, there is a delay of several seconds between clicking Play and the presentation appearing on the external display. Animations such as Dissolve do not play properly, and embedded videos fail to play at all. For comparison, the exact same Keynote file runs perfectly smoothly on my 2017 12-inch MacBook.

Interestingly, everything works normally when the external monitor is used in Mirror Display mode. The problem only occurs when using the monitor as an extended display.

I've tested several different monitors. I'm using Apple's official USB-C Digital AV Multiport Adapter together with a high-speed HDMI cable, so I don't believe the adapter or cable is the cause.

I found one post in the Japanese Apple Support Community describing the same symptoms, but apart from that I haven't been able to find any reports of this issue online.

I also tested the same setup on a display model at an Apple Store in Japan, and it exhibited exactly the same behavior.

Has anyone else experienced these issues when giving Keynote presentations with a MacBook Neo? If so, were you able to find a solution?

MacOS 26.5.1

iMac 27″, macOS 15.7

Posted on Jun 26, 2026 10:58 PM

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User profile for user: v1v3km
v1v3km
User level: Level 5
5,420 points

Posted on Jun 26, 2026 11:07 PM

Hi there! This is a known issue that can occur when using Keynote with a 4K external display in extended mode — the GPU has to render two separate framebuffers, which can strain performance especially with animations and embedded video. Here are some steps to help:


1. Update Keynote and macOS:

- Make sure Keynote is updated to the latest version via the App Store

- Go to System Settings → General → Software Update and install any pending macOS updates


2. Adjust Keynote playback settings:

- Open your presentation in Keynote

- Go to Keynote → Settings → Slideshow

- Enable "Reduce motion" if available, and uncheck "Show presenter display" if you don't need it


3. Change display resolution on the external monitor:

- Go to System Settings → Displays → select your external display

- Try switching from the default "More Space" resolution to a slightly lower one (e.g., 2560x1440 scaled)

- This reduces the GPU rendering load significantly


4. Disable "Automatic graphics switching" (if applicable):

- Go to System Settings → Battery → uncheck "Automatic graphics switching"

- This forces the dedicated GPU to handle all rendering, which can improve external display performance


5. Re-encode embedded videos:

- Videos in formats like .mov or high-bitrate .mp4 can struggle on extended displays

- Try re-exporting them at a lower resolution (1080p) using QuickTime or Compressor before embedding


The fact that Mirror mode works fine confirms this is a rendering/bandwidth issue specific to extended display mode, not a hardware defect. The resolution scaling fix in Step 3 tends to have the most immediate impact. Hope this helps!

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User profile for user: v1v3km
v1v3km
User level: Level 5
5,420 points

Jun 26, 2026 11:07 PM in response to Hiramasadon

Hi there! This is a known issue that can occur when using Keynote with a 4K external display in extended mode — the GPU has to render two separate framebuffers, which can strain performance especially with animations and embedded video. Here are some steps to help:


1. Update Keynote and macOS:

- Make sure Keynote is updated to the latest version via the App Store

- Go to System Settings → General → Software Update and install any pending macOS updates


2. Adjust Keynote playback settings:

- Open your presentation in Keynote

- Go to Keynote → Settings → Slideshow

- Enable "Reduce motion" if available, and uncheck "Show presenter display" if you don't need it


3. Change display resolution on the external monitor:

- Go to System Settings → Displays → select your external display

- Try switching from the default "More Space" resolution to a slightly lower one (e.g., 2560x1440 scaled)

- This reduces the GPU rendering load significantly


4. Disable "Automatic graphics switching" (if applicable):

- Go to System Settings → Battery → uncheck "Automatic graphics switching"

- This forces the dedicated GPU to handle all rendering, which can improve external display performance


5. Re-encode embedded videos:

- Videos in formats like .mov or high-bitrate .mp4 can struggle on extended displays

- Try re-exporting them at a lower resolution (1080p) using QuickTime or Compressor before embedding


The fact that Mirror mode works fine confirms this is a rendering/bandwidth issue specific to extended display mode, not a hardware defect. The resolution scaling fix in Step 3 tends to have the most immediate impact. Hope this helps!

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User profile for user: Hiramasadon
Hiramasadon Author
User level: Level 1
4 points

Jun 27, 2026 12:40 AM in response to v1v3km

Tanks v1v3km.

I wasn't aware that this was a known issue.

Both my operating system and Keynote are up to date with the latest versions.

Disabling "Show presenter display" did indeed improve the performance.

However, I would like to use an extended display so that I can see the next slide and my presenter notes while presenting.

I am able to use an extended display without any issues on my 12-inch MacBook (2017), whose graphics performance I believe is lower than that of the Neo.

I also tried lowering the resolution of the external display, but it didn't improve the situation.

Is it really impossible to use Keynote with an extended display on the MacBook Neo?

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Keynote issues on MacBook Neo with 4K extended display

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