subset filtering is done on each request which is suboptimal

[Francis De Brabandere]

title says it all

[Julien Richard-Foy]

Well, with 0afffee you can partially apply subset in order to perform the filtering process only once:

val jsMessages = new JsMessages
val filteredMessages = jsMessages.subset("foo", "bar")

val index = Action { implicit request =>
  Ok(filteredMessages(Some("window.Messages")))
}