Open Radar

 
For me, iOS 9 was unbearably slow in beta 1 and 2. Beta 3 was fine and back to almost the same performance as iOS 8. Beta 4 is back to being crazy slow. This is on an iPhone 6 Plus.

Symptoms:
* Tapping home button to wake screen sometimes takes several seconds. When screen wakes, it frequently activates Siri (because it thought I long-pressed the home button, presumably because CPU was so crazy maxed out it couldn't process the button-release event in time).
* Likewise with tapping SpringBoard app icons, it'll go into shakey-rearrange-icons mode.
* Entering and exiting apps are often one or two frame animations, with the whole phone being unresponsive and stuttery for roughly 3-6 seconds (beyond the loading time for the app)
* Memory rarely fits more than one app.
* Apps are crazy crazy slow, as if they are absolutely CPU starved
* Music playback in Spotify is stuttery when I do anything with the phone
* Camera app takes >10s to start, with a single frame animation, and camera being black for a looong time, then often crashing back to lockscreen, and then working when you try it again.

Some of these behaviors were more common in beta1 and 2, not sure which ones are still common in beta 4.

I tried Instrumenting the system, and saw lots of cloudd, aggregated, backboardd and other daemons using >50% cpu; but I only sampled for a few minutes. Another culprit seemed to be VoIP apps: Skype, Hangouts and Viber were all waking up roughly every 5s, which seemed WAY too often to me.

Performance is still bad on Beta 5 and after uninstalling all the VoIP apps, but not quite as described above. Memory pressure still seems to only allow a single app; and some times CPU is completely hogged (phone gets warm + animation stutter + apps take forever to launch).

My QA friend at Spotify describes the exact same behavior on iOS 8, so it might not be iOS 9 specific? Not sure what triggers it though; I did not have this behavior on iOS 8.