Filters clarification

[jsumners-nr]

unplugin/docs/guide/index.md

Lines 260 to 261 in 4aa87b3

	To optimize performance in native bundlers, leverage the `filter` option in `resolveId`, `transform`, and `load`
	hooks to exclude files that don’t require processing.

What does this sentence mean? Are files in the "exclude" filter just not transformed? Or are they not included in the final output at all? How do we debug these filters to see that our configuration is doing what we think it should be doing?