ID 481410 - Nuke can't playback UHD cached frames at 24 fps when monitor out is enabled

Problem summary
Nuke can't playback UHD cached frames at 24 fps when monitor out is enabled
Tested with:
Changing output resolution or bit depth for the monitor out device makes little difference, only changing the format resolution made a significant difference
Nuke Studio plays back UHD footage with monitor out enabled without issue

From testing, sometimes Nuke plays back faster to start with, around 20 fps, but the more settings you change for the monitor out, the slower it will get, down to 10 fps. Changing settings back doesn't recover performance. For example, changing to 10 bit, then back to 8 bit.

Customer reported version
nuke.13.0v2

Customer reported platform
windows10

Steps to reproduce

1) Open Nuke

2) Paste the following ColorWheel node:

ColorWheel {
 format "3840 2160 0 0 3840 2160 1 UHD_4K"
 gamma 0.45
 rotate {{frame*12}}
}

3) View the ColorWheel node and playback the timeline, once cached, it will play at 24fps

4) Enable monitor out, using the Floating window or other monitor out hardware, setting the frame rate to 24fps and any resolution.

5) Playback the viewer, it now won't playback at 24 fps

6) If you don't see a significant performance drop, if you set your monitor out device to 10 bit, cache the viewer, then go back to 8 bit, the performance should be worse. 

Expected behaviour
For the framerate to stay consistent when playing back with monitor out enabled:
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Actual behaviour
Playback performance massively drops, depending on hardware, can be over 50% slower:

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Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Nuke 13.0v2 - Windows 10, CentOS 7
Nuke 13.0v1 - Windows 10
Nuke 12.0v1 - Windows 10
Nuke 11.0v1 - Windows 10
Nuke 10.0v1 - Windows 10, CentOS 7 * performance is better, but still not 24fps

Using:

Earliest version tested
Nuke 10.0v1 - This issue appears to be in all versions of the product