On-demand module bundling on development environment

[regalius]

Is your feature request related to a problem? Please describe.
As our user's app grows, their build time would be significantly slower since webpack needs to compile much more files than before, this will results more waiting to compile time while we develop.

Describe the solution you'd like
So my proposal is to implement on-demand module booting, module would only be built when requested, I think this would help to reduce the compile time.

Describe alternatives you've considered
We've tried to implement many optimization for webpack development build but it doesn't really add significant benefits, other easier approach is to build a module selector on start CLI, for example:

yarn start --module my_module

or if we want to work with multiple module, maybe we can do:

yarn start --module my_module,my_module2

[martinock]

I've been thinking about trying to create a copy of _route without unselected routes.

Example: We have 5 modules

yarn start --module module1,module2

Before we run the "real" start, we will remove module3, module4, and module5 routes and write the result to another files I suggest: route.development.js, path.development.js, and module.development.js. Then we use these files to start our dev server

Is it okay to do this? Or is there any better approach?