iPhone 12 animation lag caused by RunningBoard?

Apologies if this isn't the right venue for this, but I figured the developers on here might have some insight.

I've been looking into a problem which I'm experiencing on my 12 Pro, and others have also reported: when closing apps, occasionally there's a stutter in the animation, like dropped frames. It seems to start occurring after I've opened many apps since my last restart. It's been an issue since launch, on iOS 14.1, 14.2, and now the 14.3 Public Beta 2. I've also tried reinstalling iOS and setting up as a new device, with no change.

Based on when I see it, my theory for the cause is basically: when you close an app, but the memory allocated for suspended apps is already full, the OS needs to clear out some of that memory, and there's a lag/stutter in the UI while it does this.

To test this out, I plugged my phone into my Mac, and pulled up the Console app to watch for error/fault messages in the iOS log. Almost every time I close an app and see this stutter, there are error messages from runningboardd (RunningBoard), such as the following:

Code Block
error 17:38:41.087985-0700 runningboardd RBSStateCapture remove item called for untracked item <RBProcessMonitorObserver| qos:0 qos:(null) configs:{
}>


Such errors do not occur when an app closes smoothly with no stutter. It's not always the same error, but there's a pretty consistent correlation between seeing the stutter and seeing a runningboardd error.

Some light googling tells me that RunningBoard is a new-ish part of iOS used to track active processes.

Does anyone have more experience with RunningBoard errors, or has a good idea for further troubleshooting steps?
One update to this, is I've discovered this is not iPhone 12 specific, as the same animation behavior occurs in the iPhone XS, accompanied by the same RunningBoard errors.
I have the same kind of issue with my iPhone 12, this is a very good post, I think Apple should fix this problem, the overall performance of iPhone 12 series is very unpleasant.
Same exact issue on my 12 Pro. Went through device resets and restores with the issue still persisting.

Talked with Apple support and they said something about escalating this to software development, will need to follow up.
This has been happening to me since I got the iPhone 11 Pro in fall of 2019. The worst part is when the stutter hits just at the right time, it causes the swipe up to fail and you end up in the multitasking view. Very frustrating!
I experience the same stutter with my iPhone 12. Please fix this!
Yes, I’m having this same problem on an iPhone 12 Pro. I get the stutter that often times pulls up the multitasking view.
It's ruining the experience of iPhone, and some users started complaining the App developers about this issue.
I thought it was a hardware problem, and your post reminded me that it was probably an under-optimization of iOS.
The animation performance of iOS now is terrible,Craig should pay more attention to basic experience, otherwise A14 Bionic will just become a vase .
Same issue on my iPhone 12 Pro since day one. Hope it gets fixed soon.
It's definitely not specific to just defective phones. I experienced it last year on the iPhone 11 Pro and Apple replaced it. The replacement exhibited the same behavior as well. Now my new iPhone 12 Pro experiences it also. I have an open support case with Apple. The last update I heard was that engineers are looking into it and to install any new updates. After over a year of anxiously installing every new update, I have to say I'm no longer holding my breath for a fix any time soon.
iOS 14.4. No fix whatsoever. My 12 Pro Max has terrible lag spikes while opening multitasking window. Did anyone successfully get a replacement due to that issue?
Hi folks. We'd like your help understanding this issue better. Please use the Feedback Assistant app or website to file this feedback, so we can gather logs and other information for our investigation. Sign in with the Apple ID you use for the Apple Developer Program, Compose new feedback, and choose iOS and iPad OS, then App Switcher for the Area and Application Slow/Unresponsive for the type of feedback.

Once you’ve filed, add your feedback number to this thread. After you file, you’ll be provided a special debug profile and instructions to install it and gather a Sysdiagnose and other data.

Thanks for your help,

—jasonag.
Thanks Jason! I really hope you guys can fix this. It is driving me crazy because it breaks the main navigation gesture. If it was just animation stutter, I think most people wouldn’t care much. But when you swipe up to go home and the phone stutters and you end up in the app switcher instead, that’s super frustrating. My feedback number is FB8991103. Please let me know what to do next. Thanks!
My Feedback number is FB8991127
My Feedback number is FB8991146

I really hope you guys can fix this. It is driving me crazy because it breaks the main navigation gesture. If it was just animation stutter, I think most people wouldn’t care much. But when you swipe up to go home and the phone stutters and you end up in the app switcher instead, that’s super frustrating. 
iPhone 12 animation lag caused by RunningBoard?
 
 
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