Specs? A decent 2011 PC is still pretty viable today.
I'll chime in here.
i7 2600K OCed to 4.2
8GB Ram
Two 1TB HDD 7200RPM
ATI/AMD 6870
First few times I booted, it was slow. I was noticing a lot of HDD usage, which was causing everything else to go slow. I ended up making exceptions for the following programs in defender (all found in system32):
dwm
searchindexer
svchost
I saw the load drop immediately.
Two more reboots and it was very close to 8.1 performance, but a bit slower.
I have also noticed longer boot times.
This is on a upgrade and then used reset function to wipe drive and start clean. It sat on "resetting this PC 99%" for 5.5 hours before resetting and starting the clean install.
The process time from starting the upgrade to having a functional working PC (clean boot) was over 10 hours. Too long, MS.