Shouldn't be necessary after a proper upgrade. Maybe wipe the Dalvik partition yourself afterwards if your vendor is incompetent?

Yes, the "upgrade" to ios 11 slowed down app load/switch times on my ipad by several seconds, even after a full reset (made no difference). It's nonsense that I am now stuck with it.

Define "full reset". Did you wipe and re-install via iTunes? I seem to recall reading recently that can make a big difference.

Maybe it's from this link on Daring Fireball? [1] A wipe and reinstall via iTunes is also an extremely painful process. Since the ability to transfer apps from iOS to iTunes was removed long ago (for reasons — like App Thinning — that don't make any sense to me), once the reinstall and restore of the data (alone) from iTunes is done, one would have to wait a long time for all the apps to download via WiFi from the App Store. For people with many apps and games (that are quite large), this wipe and reinstall would cost them several GBs in download traffic and several minutes to several hours (depending on where one lives and the Internet connection).

[1]: https://daringfireball.net/linked/2017/12/22/glenn-iphone-sl...

Yep, thanks.

No, reset from ios. I'm not aware of a difference with doing it from iTunes, either way you get an empty ios that first asks you the os language you want.

I would give it a try. A reinstall of the OS is more thorough than wiping the data from it.

http://mglenn.com/blog/2017/12/22/apples-bungled-battery-fea...