[maxxxxx]

It always infuriated me that MS usually wasn't using the tools they gave to developers for their own stuff. I think it has got a little better in the last years. Now they seem to be using UWP to some degree. But before that they didn't use Winforms or MFC. WPF only for VS 2010 and up.

[userbinator]

If you've ever used any other applications written in pure Win32 you would know why --- the efficiency difference is enormous. They did start using more managed code in the system starting with Vista, which resulted in all the complaints about it being slow and bloated. I suspect there's been even more of it added since then, because the Win10 explorer.exe on a recent quad-core i7 system with an SSD still manages to respond more slowly to actions like opening a folder than XP's on a 15-year-old PC with a regular HDD...

[maxxxxx]

"If you've ever used any other applications written in pure Win32 you would know why"

I have written pure Win32 and I know that...

[machinecoffee]

MFC I'm not so sure about, but ATL or even better WTL would probably do the job.