I think it's really interesting the way programmers will use phrases like, "it feels heavy", as a way to describe using programs that contain unused features. I'm guilty of the same. Powershell "feels heavy" because it is a lot more sophisticated than batch, you can do all sorts of cool things with WMI or use data structures, but in the end, what does programming in batch actually gain you? If performance is such a problem that you notice a performance penalty when switching between shells, something is seriously wrong.

But I'm guessing you don't really notice the performance difference, you just feel the weight of unused features.