[luatex] Removing the zero-initialization of an array can speedup LuaTeX on plain TeX document by 25%

[Joseph Wright]

On 01/09/2024 01:28, Reinhard Kotucha via luatex wrote:
> Regarding performance tests, there are a few things worth to be
> mentioned.  You get different results in different environments.
> First of all, in TeX Live luatex.ini contains the line
>
>    \input load-unicode-data.tex
>
> This huge file blows up the format file and increases startup time
> significantly.  AFAIK it's currently only used by LaTeX and can be safely
> removed from all plain TeX formats.

load-unicode-data.tex initialises the values for \uccode, \lccode and
\sfcode based on the current Unicode release. As such, it's intended to
set up for unpredictable character set usage: if you know which
codepoints will be used, you could avoid this, but in a general sense
that's not true. Perhaps you are thinking of the additional data loaded
in the LaTeX format by expl3, and used for things that are not covered
by the classical TeX structures (e.g. one-to-many case changing)?

load-unicode-data is intended to be generic, so if adjustments are
needed, these can be discussed so they also apply to XeTeX.

Joseph