Again, not a single one of those things occurred in any of my 2 phones or the ones I've set.
So, if you have Factory Reset it, have you done it via menu or Recovery menu, some think it does the same, but because of old habits and experiences where I saw Factory Resets leaving some apps and Data intact, since then I've never done it via the menu and I've always done it via Recovery Menu. Do a Wipe cache Partition and then do the Wipe data/Factory Reset also, obviously if you have a good backup of your files and are willing to try once more.
I think you should have one or possible even more of your default apps causing havoc, so if you want to try something before the factory reset, you can always boot in safe mode and work as you normally do on your phone, if it behaves better then it's a rogue app that's is causing your issue, then do the rest for sure.
First thing I'd do after the reset is to set it as a new device, not restore from a backup, then look for my thread about Tips, tweaks and tricks and believe me, remove all bloatware you'll never use, Samsung, Google and now even Microsoft, in addition to any carriers bloat. Remove SVoice from Samsung, if you are like most of people that hate the new Briefing app, remove it, if you want the same but not so intrusive, just install the original Flipboard app.
With the above and enabling Developer options and changing animations in there to. 0.5x or off, performance should be greatly improved. Try and see and then let us know if it worked for you.