As noted in the sibling comment, Notepad does A LOT of stuff, some of it to deal with users who use (abuse?) it to do things it was never intended to do, and MS

As noted in the sibling comment, Notepad does A LOT of stuff, some of it to deal with users who use (abuse?) it to do things it was never intended to do, and MS saw fit to keep it doing those things for compatibility. It did these things prior to the update, and knowing MS I imagine it's had to maintain some compatibility with the older version. That said, I've not encountered the same slowness issues since updating that are discussed here. I'm not a fan of the menu animations, but it's a minor nitpick. For editing huge texts it is significantly more efficient, in my experience. I remember turning off word-wrap in the old notepad after loading a huge log file, then having to wait minutes for Notepad to become responsive again. Yeah, I know, anecdata.... Edit: The source code to the older Notepad is rather easy to find online. I won't link to it, but it's an interesting read.