Re: Low redisplay performance (23 regression)

["Tobias C. Rittweiler" <tcr@freebits.de>]

David Reitter <david.reitter@gmail.com> writes:

> [Emacs 23.x performance regression]

On a related note, I notice a big slowdown for `end-of-defun'.

In a .lisp buffer with 6371 lines, running the following

  (benchmark-run
   (dotimes (i 100)
     (beginning-of-buffer)
     (dotimes (i 200)
       (end-of-defun))))

yields the folloing timings:

  GNU Emacs 22.1.1     -->  (4.323907 2 0.07007399999999997)
  GNU Emacs 23.0.60.1  -->  (7.5862680000000005 1 0.048462000000000005)
  GNU Emacs 23.0.92.1  -->  (7.610763 2 0.06742599999999999)
  (built on 2009-04-29)

As I use `end-of-defun' in my customized
`font-lock-extend-region-functions' this does have an impact on the
overall performance of fontification for me on large files.

What is the reason that `end-of-defun' is an _order of magnitude_ slower
than `beginning-of-defun'?

  -T.