It looks like they did it in a hurry (on the next day) just after https://hacks.mozilla.org/2014/05/how-fast-is-pdf-js/ https://hacks.mozilla.org/2014/05/how-fa

It looks like they did it in a hurry (on the next day) just after https://hacks.mozilla.org/2014/05/how-fast-is-pdf-js/ https://hacks.mozilla.org/2014/05/how-fast-is-pdf-js/ was published? Competition FTW!