Because people ask for an IDE, rather than an editor, I will say :
Vim + terminal(s) + containerization (e.g. Docker CLI, Python venv) + live reloading (e.g. nodemon or inotify or in the browser using e.g. server side events) + repository management (e.g. git in CLI to juggle between branches, push/pull local/remotely)
IMHO this is very VERY light (0 wait even on a RPi Zero) and yet very flexible.
Also most of that can be “saved” via e.g screen
the CLI tool, allowing to have named windows in a terminal and a lot more than to e.g. screen -raAD
, locally or remotely.
… actually (tip fedora hat) not but seriously actually most of what we NEED is fine that way. It sounds ludicrous then you try Sxmo on a phone and you can’t help but GENUINELY wonder “Damn… did I get scammed all those years?”