If VSCode and Webstorm are heavy, you will be very disappointed with every IDE I know of. None are lightweight. That's kind of the opposite of an IDE (Integrated development environment).
If you just want to edit code, the lightest weight editors are things like VIM (which doesn't have to just be an editor) and Notepad++. Next up the food chain are the editors with extensions/plugins/other capabilities, like VSCode, Atom, Sublime, Brackets. A step up from there would be the the specialized editors/IDE's - like PyCharm and Webstorm. Finally there are the enterprise level IDE's - like Visual Studio, IntelliJ, Eclipse.
With the exception of VIM (it's really a different beast)...
The tools get "heavier" as you ask them to do more things. Linting adds weight. Code completion adds weight. Project/Solution management adds weight. Integrated source control adds weight. I have switched from Visual Studio as my primary tool to VSCode as my primary tool because most of what I do day to day doesn't require Visual Studio. I did have to learn how to use it VSCode better, though.
If you primarily work on the Microsoft stack, I would consider Visual Studio and VSCode to be optimal choices.
If you work primarily in python (regardless of stack), I would consider the python specific tools first.
If you need something that handles more languages and is cross-platform, I would consider Eclipse or IntelliJ. If those are too "heavy" for you, then I'd look at VSCode, Atom, etc.
If all of those are just too heavy for you, VIM is an excellent choice. It is amazingly configurable and can do almost everything the other tools can do - provided you configure it to do so. It seems to take a couple of months be get comfortable with it as a basic editor (and you have to be willing to learn to really use your keyboard). You can then add capabilities to it as you need them.
I think, in the end, you will adjust your definition of what "heavy" is... or you will use a tool like VIM.