In a largeish buffer, org-fold-core--fix-folded-region significantly
slows down typing to a point where I have to wait a few milliseconds to
see the characters typed.  With emacs -Q, the slow down isn't as bad as
with my full configuration but it is still noticeable.  Setting
`org-fold-core--ignore-modifications' to t makes the lag go away.

The large buffer that I type in has a PROPERTIES drawer for every
heading there is and I have 481 such headings.  There is one heading
with a couple of drawers that are hundred of lines long and might even
have long lines.  I can send this heading if you would like privately.
The buffer has the following STARTUP options set:

    #+STARTUP: fold num

I have attached three files:

    · org-fold-core-slow-profile: profiler report in the said large
      buffer with my Emacs configuration.
    · org-fold-core-fast-profile: profiler report in a fresh new org
      buffer with only two lines, also recorded with my Emacs
      configuration.
    · org-fold-core-emacs-Q-still-kinda-slow: profiler report in the
      said large buffer recorded in `emacs -Q'.

If this is not enough info, please tell me how to help.  Thank you.