Personally I think it has to do with the drives themselves. When my Seagate drives were starting to die my POST times were about twice as long as they had been and the boot to windows logo from POST and subsequently from logo to login screen were all longer.
After replacing the drives all the times were reduced.
4690K @ 4.6Ghz
2X4 Gigs G Skill F3-14900CL8-4GBXM
EVGA GTX 760 SLI
Fractal Design Define R5
Dual loop WC
Some other stuff,
Even more stuff,
If the automobile had followed the same development cycle as the computer, a Rolls-Royce would today cost $100, get a million miles per gallon, and explode once a year, killing everyone inside. --Robert X. Cringely, InfoWorld magazine