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:
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?