Tahoe beta - slow virtual display?

[piokaczo]

Hi,

After updating to Tahoe beta (I am right now at its newest version) I have noticed quite slow visible refresh rate in mirrored virtual display with highdpi. It's like 20 fps maybe. Obviously the refresh rate reported by monitor is way bigger. This does not occures when virtual display is not enabled. Prior to upgrading to MacOS Tahoe this was working flawlessly so probably something related to new OS.

This is my spec:

• Betterdisplay Pro Version 4.0.4 Build 45613 (also in latest version 3 which I used initially)
• 2023 MBP 16" with M3 Max
• External monitor native resolution 7680x216
• Monitor connected through CalDigit TS4 by DisplayPort cable (DP 2.1 and DP 1.4 tested, using DP 2.1)
• CalDigit connected to MBP through Thunderbolt 4
• Virtual screen set to 5888x1656 (tested both in 120hz and 60hz)
• External monitor set to extend mode (but clone mode tested as well)

BTW is there any way to force external monitor to go into 120hz? It is available in system settings dropdown when BetterDisplay is turned off yet when virtual display is engaged it drops immediately to 60hz.

[waydabber]

Hi there - are you mirroring the virtual screen to the display or using PI or streaming? I see your display is set to extend mode. If you try mirroring the virtual screen, do you have the same issue?

[piokaczo]

Hi @waydabber, sorry for late reply as I was off.

I work in clamshell mode so not using macbook screen at all when external monitor is connected - thus extend mode is usually disabled (unless I open the macbook lid). The virtual display is set as main display, physical one is set as a clone of virtual one. Virtual one is MIRRORED to physical one - not streamed.

[waydabber]

I see. Well, I am not sure what could be wrong. I tried the mirroring scenario with a 5888x3312 HiDPI (that is 11K) virtual screen mirroring to a native 8K panel (7680x4320) similarly on M3 Max and things seem as usual (60Hz). Do you have the same with Tahoe RC?

[piokaczo]

Yes unfortunately on RC too. But it looks like opening MacBook and closing it somehow fixes that at some point at least this is what I see. I will investigate further next week and check if reintializing display or any other fiddling will help.

Maybe this is also due to related to refresh rate issues in having? I see when initializing virtual display that my monitor goes into 60hz from 120hz with vrr without a way to select 120hz (system display settings just starts to show only 60hz there).

[waydabber]

Not sure why. I think you should be using the virtual screen at 60Hz for optimal performance.