bug#57150: 29.0.50; [PATCH] Add test coverage for overlay modification hooks

[Richard Stallman]

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  > The problems with overlays in Emacs are much wider than just Org.  Our
  > performance sucks in many cases because of that.  Just two examples
  > that were mentioned lately in the "long-line optimizations"
  > discussion: show-paren-mode and isearch-lazy-highlight -- each one of
  > these two is capable of literally bringing Emacs to its knees,
  > response-time wise.

The first question is, should these use text properties instead of
overlays?

Are they using many overlays to highlight many potential matches in a
long buffer?  If so, would it make sense to show, at any time, only those
that are near point?  When you move to a far-away part of the buffer,
it could add highlighting to the matches near there.  But maybe it
can avoid ever trying to highlight more than a few parts of the buffer.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)