speeding up writing of pdf objects.

[u-fischer]

Currently before writing a named object to the pdf, the code has first to look up the type of the object. When many objects are written this gets very slow. I would suggest to add variants where the type can be given directly:

\DocumentMetadata{uncompress}

\documentclass{article}
\usepackage{l3benchmark}
\begin{document}
abc
\ExplSyntaxOn

\typeout{obj write}
\benchmark_once:n{\int_step_inline:nn {1000}{\pdf_object_new:nn {testA#1}{dict}}}
\benchmark_once:n{\int_step_inline:nn {1000}{\pdf_object_write:nn {testA#1}{/A/B}}}

\cs_new_protected:Npn \__pdf_backend_object_write_dict:nn #1#2  %pdftex version
  {
    \tex_immediate:D \tex_pdfobj:D
      useobjnum ~
      \int_use:c
        { c__pdf_backend_object_ \tl_to_str:n {#1} _int }
        { << ~ \exp_not:n {#2} ~ >> } 
  }
  
\cs_new_protected:Npn \pdf_object_dict_write:nn #1#2 %#1name, #2 content
 {
   \__pdf_backend_object_write_dict:nn {#1}{#2}
 }  

\typeout{direct dict}  
\benchmark_once:n{\int_step_inline:nn {1000}{\pdf_object_new:nn {testB#1}{dict}}}  
\benchmark_once:n{\int_step_inline:nn {1000}{\pdf_object_dict_write:nn {testB#1}{/W/Z}}}
\ExplSyntaxOff

\end{document}

objwrite
0.212 seconds (1.01e6 ops)
2.2 seconds (1.05e7 ops)  %writing with lookup
directdict
0.744 seconds (3.63e6 ops)
0.004 seconds (1.91e4 ops) %writing without lookup