Sabriena's laptop that we bought her a while back just doesn't perform like I reckon it should, even after a few tweaks.
I decided that reinstalling to cure it of the HP installation would probably be the best bet, so I went and found a download for an untouched Windows 8.1 installation media, and burned it to a disc. For some reason, it asks for a product key - no problem, I wrote that down. It still won't take it!
It turns out that I downloaded Windows 8.1 "Single Language" which is different from "Windows 8.1" (which is further different from Windows 8.1 "Pro" and "Enterprise" and who knows what else). It turns out that, despite installing virtually all the same shit to the hard disk, there's no way to correct this licensing issue without reinstalling (I tried for a good 20 minutes of Googling and using slmgr).
So I went again, and downloaded another image (for posterity, I used the process described in this EightForums thread), burnt it and installed without issue.
Performance is much better, but still not amazing. I can't really figure out why either, the difference in specs between my laptop and hers aren't that huge (different number of cores mainly - EDIT: Actually, yes they are that huge, almost 2x difference in passmark, ouch!), but the main grievance still seems to be the disk performance. Maybe an SSD is in her future?
Anyway, back to my licensing gripe. I'm assuming (perhaps incorrectly) that this is some form of anti-piracy measure? I have to wonder why. It's worth noting (as I mused on IRC) that if I'd pirated Windows 8.1, I could simply have activated the "Single Language" version and been on my way... by trying to do the right thing I was actively inconvenienced. I really have to wonder how bloody smart that move is on Microsoft's part.