It should not take apps 10 seconds to launch on an iPhone 6 running iOS 11. Something probably went wrong with your upgrade, which does happen. Have you tried taking a local backup, doing a factory reset of the phone, and then restoring the backup?
On every computer I own and every non-cloud server I manage windows update has broken at some point in their life-time (often silently). 5 out of 5. So it's not just Apple. And quite a few of them it's happened more than once.
One server I noticed the other day because of Meltdown. My laptop got stuck on the creators update. Before that I'd noticed the laptop had got stuck trying to upgrade a driver because it's fan kept going mental every day if I left it unattended for 5 minutes because windows update is so poorly written. I had to hack the .Net optimization service to stop it running the 32-bit version because it would constantly fail and then try and re-run itself. I use .Net framework every day and the optimization service seems to be entirely devoid of purpose.
I swear more CPU and electricity has been spent on windows update and badly written maintenance tasks on that laptop than any of my programming, building, compiling, etc. The fan is moderately noisy and whenever it spins up, it's always a windows update or maintenance task. Or skype. What on earth they've done to that program I do not know, but it's rubbish.
My refurb X220 came with Win10, and it would just sit there, burning 25-30% CPU for apparently no reason, doing something probably update related. The battery isn't exactly new, but it's a 6-cell with about 40Wh capacity remaining. That should be good for more than just 1 measly hour.
Apparently Win10 sometimes needs to sit like that for a couple of days after installing, for reasons.
So I ditched it and installed Linux Mint. And whattayaknow, it installed faster, it didn't need any additional drivers and it doesn't idle at 30%. Everything Just Works™.
A 2011-vintage laptop with an i3 (plus 8GB RAM and an SSD) is still a perfectly usable machine today, if you pick the right OS.
I'm still getting that 9-cell battery of course, because you can still get brand new ones.
Yeah, if you investigate, which admittedly takes a lot of effort, one of your maintenance tasks will be erroring. The memory one seems to be one of the worst and a lot of people see bug reductions in the tasks runtime when they do.
See for example: http://mglenn.com/blog/2017/12/22/apples-bungled-battery-fea...