My Iphone 6 plus has been insanely sluggish after updating to IOS 9.0.2 (I bought it new on Aug 8 2015). I have done the home button/power button reset dozens of times and never fixes the issue. I have looked on chat boards and followed suggestions of clearing APPs and Pictures. This is 64 GB phone with 50+ GB free. I have turned off most features I.e. Hey Suri, parallax viewing, contrast settings, wifi assist, heck I went to gray scale to see if it would help and nothing helps. Overnight it seems to be better as the phone works normal after it hasn't been used for 8 hours then after awhile of use it keeps getting worse where the screen locks up for minutes at a time and will eventually work for awhile (sometimes it takes 10 minutes or more before I can use it). If I hold down Suri I can have Suri open an App but I cant do anything in that App. It is like the RAM isn't cleaning itself as it should. Is there something other than go back to previous OS where it worked to fix? Is there a way to see the RAM being used like you can on a PC and control what is being used at once? Anyone else with this same issue?
Any help would be appreciated!
If you have an Apple Store nearby take it to them so they can look at it. If they can't fix the issue and they determine it's a hardware issue they will replace it. If it's connected to the latest iOS update then there may not be a fix until the next update releases. I didn't update to the latest update but I do notice a bit of sluggishness. Not nearly as bad as you're experiencing and I have significantly more on my device (only 19gb's free on my 64gb plus).
Good points by kaebfly. I would suggest backing it up.. then doing a factor reset.. use the phone a tad before you restore from backup.. that will sometimes resolve the issue.. and the other plus is if you go to Apple, you can say you already tried this. The key is use the phone a bit vanilla before you restore from backup. Its a little bit of a pain but will help in getting it swapped out from Apple if that is what is needed.