And there is an idea about that which you can vote: https://connect.mozilla.org/t5/ideas/add-ability-to-translate-input-text-in-a-standalone-page/idi-p/10849.
@Asperamanca thanks for the feedback, we'll work on improving performance when zooming.
@pbp we thought it would make sense to open the PDFs in Firefox because, coming from the web, they are potentially insecure and our PDF viewer is secure by defini...
