Use httpuv staticPaths
httpuv somewhat recently added the feature that static files can be served without calling R code. On top of potential performance improvements httpuv also enables HTTP caching directives for static files, so that files don't have to be re-transmitted every time a page is viewed in browser (for example plotly is around 3MB of minified javascript which is.. noticeable).
plumber could be extended with a new slot staticPaths which is a named list specifying which URLs are mapped to local directories (much like @assets does now).
I could probably prepare a pull request if wanted.
A PR would be great! Thank you!
Bonus request: Have the ability to retrieve all of the files in the static path for path information for OpenApi.