Paint.NET :: Simple Way To Smooth Round Icons?

Searching for how to simply, quickly smooth round edges, I learned a lot of other things I'd been wondering how to do in PDN.  But I didn't find a simple way to smooth round edges of non professional grade (not art) round outer edges.  Say, for a Windows icon.
 
Even drawing the circle on a 32 x 32 background, when saved as png then opened in Greenfish Icon Editor & converted to ICO, the real icon (say on desktop) is still a bit jagged in places.  The points at 0, 90, 180, 270 deg are obviously flattened & rest of circumference is a bit jagged (not terrible, but...).
 
I tried several tools to smooth edges a bit, but of course pixels are square...  Read numerous posts - like [URL].....

This WAY overkill for what I'm doing - right now.  Useful for later.  All I want is circles or rounded corners on simple objects w/o spending much time - not for this type stuff.  I learned good techniques useful for higher quality work.
 
PDN doesn't seem to have a simple, quicker way to half decently smooth circles / corners.  Everything I tried just followed the square pixel edges or is quite tedious.  Greenfish has some pretty decent tools - for making icons.  But, smoothing rounded edges for something in the 32 px wide range is still pretty time consuming.  Needs an algorithm to smooth circumferences.