Frame rate is locked to 60FPS on devices with frame rate optimization

[ajinasokan]

All Flutter apps seem to be locked at 60FPS on One Plus 7 Pro that has 90Hz refresh rate. Every other app including Native apps and OpenGL games runs at 90FPS. Because of this Flutter apps feel slow compared to the rest of the operating system even though there are no performance issues or janks.

It seems apps have to somehow notify the OS that it can do higher framerates. And One Plus OxygenOS seems to do this check and switches between 60 and 90 FPS modes. This XDA article explains how this works and how you can force all apps to use 90FPS. After applying the change mentioned in the article Flutter apps run at 90FPS.

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• No issues found!

[ajinasokan]

Here are some slow-motion videos of Flutter app and Native app.

[Zazo032]

Could it be related to OxygenOS locking some apps to 60fps to save battery?

There's a post in XDA that shows how to force 90hz on all apps, could you try a Flutter app after forcing it?
https://www.xda-developers.com/oneplus-7-pro-true-90hz-display-mode/

[tottomotto]

@ajinasokan can you please use the flutter profiling explained here and post the results.

[ajinasokan]

@Zazo032 Yes. And Yes. I have mentioned this in the second paragraph. It runs at 90FPS after that.

@tottomotto This is not a performance issue. The app is running perfectly fine without janks and frame drops. Problem is that the number of frames is locked to 60 instead of 90. And as I mentioned in the issue, the problem is gone if I force the device to use 90Hz always. So this is something about letting the OS know that Flutter is capable of doing 90FPS.

[tottomotto]

There is a commit merged in master which might be connected to this.
Can you switch to the master channel and try if the issue persists?
@matthew-carroll can you help out here?

[matthew-carroll]

Is this a regression or a new a problem on a new device? If it's the latter, then the referenced commit wouldn't be related.

Maybe @chinmaygarde or @jason-simmons have some thoughts on this.

[ajinasokan]

@tottomotto I tried the master channel. But it doesn't seem to fix the issue.

@matthew-carroll This is an issue in One Plus 7 Pro AFAIK. I'm not sure about other Android phones with a higher refresh rate like the Razor phone with 120Hz.

[kazenokage]

Sounds a bit like this: #31086

[ajinasokan]

@kazenokage I'm not sure about that. That looks more like regression due to the higher sampling rate. Here it is a lock in refresh rate and gets solved by disabling the optimization of One Plus just by changing the config like this:

adb shell settings put global oneplus_screen_refresh_rate 0

So this is more like a configuration issue rather than a regression.

[yekta]

I'm having the same problem. Native apps are running at 90 fps but our Flutter apps are not.

[jckpn]

Having the same problem on my Razer Phone at 120 Hz. Even when scrolling on PageViews, it will appear to be smooth and then stutter near the end of the page-snapping animation. I'd actually argue the app seems more stuttery than on my Pixel 2 locked at 60 Hz.

On a possibly-related note, I'm having very conflicting reports of smoothness from users of my app that DON'T appear to be spec-related. Specifically OnePlus and LG owners are complaining that the whole UI has dropped frames. However, on my Pixel 2 (and what most users are saying) it runs incredibly smooth as I would expect, despite the Pixel 2's relatively low specs compared to most OnePlus devices. When setting my Razer Phone to 60 Hz, I get this exact same issue. Super weird!

P.S. this seems true for every Flutter app I've tested, including the Flutter gallery. 120 fps appears like 60 and 60 fps appears like 30 with LOTS of random dropped frames.

[ping996]

How to get the framerate of flutter for desktop app?

[ajinasokan]

@ping996 You can enable the performance overlay to see if there are any janks. If none then the app is most probably running at the framerate of your display.