This has been a long time issue that would be nice to get resolved.
If there is a blank document that has only one line and you start typing, it is VERY SLOW and the squiggly red underlines (for misspelled words) appear far below the first line, as if the words were on line 15 or something. Now, as soon as you hit enter and the document has 2 lines, the problem goes away and the squiggly red lines are redrawn correctly.
So the problem only happens when:
1. The document contains only one line
2. Live spelling (with Addict spell checker) is enabled
See screenshot... look at where the squiggly red line is drawn where there is no document (because it's only 1 line).
Any ideas? Can you fix this?