I regularily edit pages with fairly long text in Icelandic, a language which uses diacritics quite a bit. If the text gets to be more than a few hundred words, the text engine buffer starts acting up, especially when using accents. It will enter two or more accents in addition to the intended accented letter, sometimes mangling the order of letters too, always being laggy too. This is NOT a new problem, but I feel it has become much more pronounced in CC 2018.

In the attached screenshot the intended text "fréttastjóra að gefa því" has appeared as "´fr´´éttastj´ór´a að gefa þv´í"