Windows takes 10+ minutes to boot with black screen — Solved!
Just a quick note for anyone struggling with this. This is talking about the infamous case after the Windows logo, there is a black screen for 10 minutes until Windows shows the welcome screen. Caps Lock key is unresponsive during that time.
After struggling on and off for a couple of weeks, the culprit was discovered to be a freaking font file!
Failing with Windows EFS
It turned out that when I installed .otf files from my Desktop, which is EFS encrypted, the font files copied to C:\Windows\Fonts appeared to be encrypted as well. Because the Windows system doesn’t have the EFS key, it would stall in the black screen trying and failing to decrypt the file.
How I solved it
Just decrypt the files before installing them, duh!