GNU bug report logs - #64391
30.0.50; buffer narrowing slowdown regression in emacs 29

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From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Andrew Cohen <acohen <at> ust.hk>, 64391 <at> debbugs.gnu.org, Gregory Heytings <gregory <at> heytings.org>, Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: bug#64391: buffer narrowing slowdown regression in emacs 29 
Date: Sun, 2 Jul 2023 11:37:53 +0200

[Message part 1 (text/plain, inline)]

How expensive markers can be when a buffer is modified is often unappreciated. Here are the results of a benchmark to illustrate the cost (code attached).
A buffer contains "abababab...", we optionally add a marker to every other position, and then time the deletion of all the "a"s. Results:

|   size | without markers | with markers |
|--------+-----------------+--------------|
|    500 |           0.000 |        0.001 |
|   1000 |           0.001 |        0.004 |
|   5000 |           0.002 |        0.089 |
|  10000 |           0.005 |        0.363 |
|  50000 |           0.024 |        9.527 |
| 100000 |           0.049 |       58.048 |

Now there's something for the curve-fitters among you.

[abench4.el (application/octet-stream, attachment)]

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