Booting up a Windows PC is slow because...

Well, I guess Windows it self isn't slow. But then there's just too much stuff that tries to run when you boot up a PC.

There's the antivirus, the firewall, the anti-adware, maybe the glorified video card driver that insists that it needs to show you "Nvidia's website" every time you turn on your computer, maybe the PC manufacturer also has tossed in some stuff running in the background, and then Windows wants to install more updates everyday, and the list goes on and on. There's just so much junk your computer has to process before you can start using it.

And then, you are greeted with thousands of pop-up windows that needs your attention. "Scan for virus now, this is important!", "Install this important Windows update NOW!", "Update your Java plugin NOW!"... All those software companies seem to think that taking care of your PC system is more important then what you actually need to be working on, for example, finishing that business document. We buy computers to get things done, not to be constantly and slavishly making sure the system is up-to-date and happy.

This madness is essentially why the experience on a Windows PC feels so bad. Anything would be better then this. It's not totally Microsoft's fault, but they let a whole industry develop into this abomination.