recently developed a winform program with C-sharp, using .net framework 4.0, because some users use XP, so they chose this .net version, but some users still do not have .net on their computers, so in order to let all users install smoothly, package .net into the installation package.

the installation package itself is only about 10m, but the .net package has become more than 70m. I want to know, is this packaging good? what is the mainstream practice?

then the program is quite stable on my computer, but there will be some conditions on win10. Later, I also did some processing, and it is basically good. But there are still a lot of problems on xp. Excuse me, is it OK to make a winform program compatible with XP,win7,win8,win10, at the same time? How to improve compatibility? How to make the program more stable?

I am self-taught C-sharp winform development. I have a language foundation, and my development is relatively fast, but after all, my experience is limited.