Why compilation with a lot of \lstinputlisting is so slow?

Question

I'm using a lot of \lstinputlisting in my document and the compilation of it is really slow. Why it takes so long? How could I make things better?

Answer 1

I guess, \lstinputlisting does a lot of parsing which takes time. The manual for the listings package mentions the option savemem which can reduce compile time if you use a lot of languages. Or use the draft option to print only captions and define labels, but omit the actual listing.

I have in my current document an appendix with a lot of listings. I omit the appendix with the versions package to save some time.