texi2any 7.0 performance regression (non-XS)

[Gavin Smith]

On Sun, Feb 12, 2023 at 11:18:53AM +0000, Gavin Smith wrote:
> No, I was comparing Texinfo 7.0.2 and 6.8 with XS modules disabled.
> A change from 23 seconds to 42 seconds is a big problem.
> 
> At the moment I'm working through the git history to try to find the
> point where the performance got worse.  NYTProf showed that a lot of
> the time was spent in _process_remaining_on_line, but I couldn't see
> from the line-by-line report where the time was going.

Indeed, the difference was at the first place I checked: on
2022-09-10, commit 46bfa18bb0, where the time came out as 43.9 sec.

2022-09-10  Patrice Dumas  <pertusus@free.fr>

       * tp/Texinfo/ParserNonXS.pm (_parse_texi, _process_remaining_on_line):
       add _process_remaining_on_line to match better with the XS parser.


In 46bfa18bb0^ (the parent commit), the time came out at 26.0 sec, which isn't
too bad.

I suspect it may just be that Perl subroutine calls are very slow, so it
is faster to inline everything into one long subroutine that is thousands
of lines long.

I'll try to look at this commit more to see if I can find anything else.