I tried creating a whole new profile, with no extensions and without importing any settings or bookmarks. The same problem still appears although it seems to take longer. Firefox does not use much RAM, only ~100MB. Password fields are not affected, but all other fields and the address bar are.
One strange thing is that there are two languages to choose from for spell checking: "en_US" (default) and "English/United States".
I tried creating a whole new profile, with no extensions and without importing any settings or bookmarks. The same problem still appears although it seems to take longer. Firefox does not use much RAM, only ~100MB. Password fields are not affected, but all other fields and the address bar are.
One strange thing is that there are two languages to choose from for spell checking: "en_US" (default) and "English/United States".