I thought this was a software issue. I have it on my 6p and had it on my 5s. No jailbreaks. It acts like it's swapping. Unresponsive, delayed response, etc. Sometimes, apps are purged from memory too quickly. It's worse with the Facebook app, which is really memory hungry, especially posting a photo. FB also wakes up from cron to check things even when not running in the background. Overall, iOS 8 and 9 have had bad memory management issues. App devs have to track and manage, because a malloc could just cause your app to get cleared from ram.

The bestI have found is: Close apps I'm not using if I am switching between two apps. Disable background for things I don't want. Don't expect anything else to stay running if Facebook is being used. When apps start flushing too quickly on background, do a hard reboot * close all apps * power off * power on holding both home + power until it powers back off * power in normally

I rarely get the chuggies with this, but it does sometimes happen. Wake up click fails to respond, or fingerprint lags longer than screen timeout. Swipe or tak hangs or does nothing.

Like I said, I has it on 5S also, and some third party chargers made it worse, but different.