[performance] Looking up every file is slow

[pedro-psb]

Hello, I've noticed that the processing here can significantly slows down building the docs, probably because of BeautifulSoup.

On my website, running the plugin added an overhead of about 27s. Because I know the files where I want the swagger-ui tags to be used, I've added a simple filename filter patch to avoid trying to lookup on every single file. That improved the performance to only 2s!

def on_post_page(self, output, page, config, **kwargs):
    """Replace swagger-ui tag with iframe
    Add javascript code to update iframe height
    Create a html with Swagger UI for iframe
    """
    if page.file.name not in ("rest_api", "rest-api"):
        return output
    ...

Proposal

My proposal is:

• Add an option (e.g, filter_filenames), which provides an optional list of filenames to match before proceding the processing.
• For backward-compat, if this option is not provided the plugin continue with its current behavior.

What do you think? I can open a PR next week

[pedro-psb]

Another similar approach is to mark specific markdown pages using the yaml frontmatter and add a global option to not process a page unless its marked.

# some markdown page frontmatter
---
swagger-ui:
  process-page: true
---

# mkdocs.yaml
plugins:
  mkdocs-swagger-ui:
    process_all: false  # default true for compatibility