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.