[2.1.12][mac] Low power mode forces 30FPS only with vsync

[A_D]

If I use Low Power Mode for my mac (MacBook Air M4), the game drops to 30 FPS, which makes _sense_ for some level due to the mode selected.
That said, if I explicitly turn _off_ VSYNC, and make no other changes to the state, my FPS runs back up to 60 with no issues, aside from expected
screen tearing.

What Happened: FPS is lower than I expected
What did I do: Enabled MacOS Low Power Mode
What did I expect: Performance on a small base to remain the same, or at least, with Vsync _off_, to not have steady 60FPS
Every time: Yes, every time.


Vsync Off:

08-01-2026, 18-29-27.png (145.75 KiB) Viewed 230 times

Vsync On:

08-01-2026, 18-30-42.png (153.55 KiB) Viewed 230 times

This behaviour is however _inconsistent_; if I have the game fullscreened (proper MacOS maximize, _or_ just taking up the full window space available without being fullscreened--Maximized?), the issue shows, however if I make the window slightly smaller, the issue goes away:
Vsync On, game not fullscreen/maximized

08-01-2026, 18-32-30.png (140.31 KiB) Viewed 230 times

While I dont have a screenshot, it also appears that switching desktops _also_ causes the FPS to go back to 60, while the game's desktop isnt maximized.
Im not sure if this is a MacOS behaviour or a game behaviour, but I'd be interested in resolving it

All of the above examples were created on the same save without a restart between

Version: 2.1.12 (Steam)
Mac OS: 26.6


With Debug Info:
Vsync On, LP Mode

Debug Info; VSYNC On, Low Power Mode On

08-01-2026, 18-39-52.png (5.57 MiB) Viewed 230 times

Vsync On, LP Mode OFF

Debug Info, VSYNC on, LP mode off

08-01-2026, 18-40-57.png (5.4 MiB) Viewed 230 times

Vsync On, LP mode On, Not FullScreened/Maximized

Debug Info, Vsync On, LP mode on, not-maximized

08-01-2026, 18-41-52.png (5.38 MiB) Viewed 230 times

Debug Info from an unmodded game, LP on, fullscreened:

Unmodded (Space Age) game, Vsync On, LP on, fullscreen

08-01-2026, 18-49-05.png (5.12 MiB) Viewed 230 times

[A_D]

Just checked; issue also occurs in current-stable; same symptoms and tests have the same results

[Rseding91]

I suspect there’s nothing to be done about this. The way vsync works means if the GPU takes longer than 1/60th of a second to render a frame the next one is forced to wait until the following 16 millisecond window, resulting in 30 FPS. Since low power mode will impact more than just the GPU timings it also means anything running CPU side likely ends up waiting slightly too long and that will also push it past the time window for a given 60 FPS frame.

[A_D]

That would absolutely make sense to me, but with sync off, or the resolution unchanged but the window moved slightly off of "maximized" (to be clear, sync still on), it maintains a steady 60 long term, which implies that this isnt the expected `I cant sustain 60 therefore pick 30` option. The GPU very obviously is not having performance issues, nor is the CPU. I'm going to grab some info from system monitor as well and share it here in a minute

[A_D]

08-01-2026, 19-46-14.png (1.38 MiB) Viewed 178 times

Using mactop because Activity Monitor doesnt show GPU Usage nicely. Definitely not the system (Activity Monitor agrees with the state of the CPU as well)

[A_D]

08-01-2026, 19-50-39.png (743.78 KiB) Viewed 172 times

This is with the window moved slightly out of alignment; GPU is keeping up just fine with the same scene and no other changes, as is the CPU

[A_D]

08-01-2026, 20-12-53.png (817.33 KiB) Viewed 144 times

And here is maximized, with vsync turned off in the settings