Re: help wanted reproducing reported performance regression in groff 1.24

[Morten Bo Johansen]

On 2026-03-17 G. Branden Robinson wrote:

> At 2026-03-16T19:19:04-0500, G. Branden Robinson wrote:
> An Arch Linux user has reported a performance regression in man page
> rendering in groff 1.24.  For "small" man pages (or collections
> thereof), it's not noticeable, but the reported degradation is
> quadratic in large inputs, roughly twice as bad as one would expect
> for 25 copies in a row of the gcc man page.
> 
> I'm not able to reproduce the problem.

I get these numbers:

  1  0.07  0.08
  2  0.14  0.17
  4  0.27  0.41
  8  0.54  1.06
 16  1.10  5.03
 32  2.17  20.80
 64  4.52  79.39
 
% uname -a
Linux mathilde 6.18.18-1-lts #1 SMP PREEMPT_DYNAMIC Fri, 13 Mar 2026 20:22:24 
+0000 x86_64 GNU/Linux

I am also using Arch Linux.

I seemed to nail the performance regression down to this commit:

  10 months ago 732b07d G. Branden Robinson         ∙ [man]: Fix Savannah 
#65190 (1/2)

Hope this is useful.

Regards,
Morten