I wonder what is so essential in iOS11 that couldn't be turned off for the iPhone 6, it worked perfectly well with iOS10, so there is no reason why it couldn't be so under IOS11. Mine is now pretty useless, I can type faster than it can display what I type, etc... I won't upgrade, this after owning a 3, 3GS, 2x4S, 2x6, 2xiPad, 1xMac Mini, 2xMacBooks, 1xWatch, 1xAppleTV... It must be possible to release an iOS update to fix this properly !!!
Sure, I could have avoided the update altogether, although I was prompted while running a GPS navigation app and driving. It was raining, dark and late so not an ideal time to look at what it was asking me to do (not that it would have been safe any other time anyway), so I inadvertently asked the phone to update later and woke up to a new iOS and very slow iPhone6.
The irony being that in the morning, it told me of a new iOS11 feature that could disable notifications while driving...
Apple, time to fix this or I could be tempted back to Android and giving up my app developper account. Honestly... you can do better than this.