I think the stock Notepad in Windows 10 is perfectly fine and speedy at least, I've never considered it too slow unless I open a huge file with word wrapping on.
Notepad2 is my all-time favorite though. It supports key features like line numbers and directionless search, but is much closer to stock than Notepad++. [0]
A huge number of security related things are going on.
Also windows logs a ton of telemetry these days.