I don't know that for sure. They might, seeing as they are very basic, but I don't know for absolute sure.

I heard that dev texture promotes higher framerate is this true?

Dev textures were intended for early development of maps when you didn't have a clear idea of what textures you wanted to use, but some people such as myself use them intentionally in final maps sometimes.

What do dev texture do?

This was made and released a year and a half ago, back when I didn't know the expectations of the Workshop.

Yes exactly ! I mean this description is bad, the way that this presentation is bad. I not being mean I giving constrive criticism

What do you mean "Show off"? Like add more pics?

Your not showing off this for some reason?