development env: is the asset pipeline expected to compile all assets or just those in demand?

I'm trying to understand if, in development, the asset pipeline is supposed to compile ALL assets found in manifest.js or just the ones that are requested.

I've been doing some testing and have found that it appears all assets are compiled even when only a singular small asset is requested. This for us can be extremely slow.

It would seem to me that all assets are compiled even if a singular, small, asset is requested. This, for us, is very slow.

In development, the asset pipeline typically compiles only requested assets and their dependencies. If it's compiling all assets, it could be due to:

Manifest Configuration: Broad directives like require_tree . in manifest.js might load everything.
Dependencies: A requested asset may depend on others, triggering additional compilations.
Configuration Flags: Certain settings might force precompilation.
To fix this:

Simplify manifest.js to include only necessary assets.
Enable debugging (e.g., config.assets.debug = true in Rails) to load assets individually.
Precompile large, infrequently changing assets if needed.
snow rider