This document is painful to edit in Firefox. It works fine in Chrome. Here's a profile: https://cleopatra.io/#report=0208026f364e6b67d1982440f9d8ecb361f615d3 Much of the time is spent re-spellchecking the entire document. (bug 1303749)
The document: https://public.etherpad-mozilla.org/p/wr-plan
Does the profile point to a Mac-specific issue (I am probably just reading it improperly but: http://searchfox.org/mozilla-central/source/toolkit/xre/MacApplicationDelegate.mm#99)? FWIW the editing seems pretty painless on Windows in Aurora.
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