Are you comparing the startup time of an interpreted language with the startup time of a compiled language? or you mean that `time python hello.py` > `( time gcc -O2 -o hello hello.c ) && ( time ./hello )` ?
I have used exercism for learning new programming languages in combination with doing Advent of Code. They have a learning track for Erlang (https://exercism.org/tracks/erlang) and you can get feedback for you implementations.
I have been using Sidebery for 2 years and never had an issue. It has all the features I need (bookmarks, tabs, panels integrated with firefox containers, themes, snapshots)
Why not Rmarkdown [0], in which you can also write LaTeX code, and if you want presentation with beamer, you just have to change a single line, so you could generate beamer presentation, html, pdf and doc from the same file. I don't even use RStudio, I just have a keybind in vim [1].