These days developers go for heavy text-editors and IDEs like InteliJ, PyCharm, RubyMine, Sublime Text with much more extensions, Vim, Emacs, etc. However, in case of the later two they are not memory and processor heavy however they have very steep learning curves.
On the other hand, GNU Nano come as a life saver. It requires a few MB of RAM(say 3-4 MB) and uses very less CPU resource. Nano is a much powerful tool with much more features.