Use storebox instead of savebox to save computing time (Feature #230)

From r1474 AMC uses savebox to save computing time when shape=oval. It will take even less time if storebox is used instead of savebox.

Following test case result justifies this.

Create a file named savebox.tex with the code:

\documentclass[a4paper]{article}

\usepackage{fancybox}
\usepackage{tikz}
\usepackage{forloop}

\newsavebox{\mybox}
\newcounter{counter}
\begin{document}

\savebox{\mybox}
{
    \begin{tikzpicture}
    \foreach \x in {1,1.001,1.002,...,2}
    {
        \draw (0+\x,0) circle (0.4cm);
    }
    \end{tikzpicture}
}

\forloop{counter}{0}{\value{counter} < 50}
{
    \usebox{\mybox}\\
}

\end{document}

This creates a tikzpicture which is used for 50 times.

The output of the command time pdflatex savebox.tex on my computer is:

real    0m8.461s
user    0m8.384s
sys     0m0.060s

Create another file named storebox.tex with the code:

\documentclass[a4paper]{article}

\usepackage{storebox}
\usepackage{tikz}
\usepackage{forloop}

\newstorebox{\mybox}
\newcounter{counter}
\begin{document}

\storebox{\mybox}
{
    \begin{tikzpicture}
    \foreach \x in {1,1.001,1.002,...,2}
    {
        \draw (0+\x,0) circle (0.4cm);
    }
    \end{tikzpicture}
}

\forloop{counter}{0}{\value{counter} < 50}
{
    \usestorebox{\mybox}\\
}

\end{document}

Here we are using a storebox instead of savebox.

The output of the command time pdflatex storebox.tex on my computer is:

real    0m2.498s
user    0m2.456s
sys     0m0.028s

Conclusion: storebox is faster!!

Things to note:

1. As the number of times savebox used is increased, the time taken to generate pdf file also increases. For example change the counter from 50 to 60,70,80,... You will notice that time also increases. If you keep on increasing the counter after sometime(counter set to 100) you may get the error: ! TeX capacity exceeded, sorry [main memory size=3000000]. But with storebox the time is almost constant. Even with counter set to 5000, the time taken to generate the pdf file was only about 3.1 seconds.
2. As storebox stores the box content as a reference instead of writing it every time to the output file (which savebox does), the pdf file generated is also smaller.

The shift from savebox to storebox will take very less effort. One has to use the package storebox instead of fancybox, use the command \newstorebox instead of \newsavebox, \storebox instead of \savebox and \usestorebox instead of \usebox.