problems with long files

[Geoffrey Hemion]

Hello,

I have put a collection of old music into a long Lilypond file. You can find it
at "http://home.arcor.de/hemion/bicinien.ly";. It consists of 27 individual
pieces, each of which is one page long, and each of which is in a "\score" of
its own.

It was written using Lilypond version 2.6.3, and compiled easily. But now I have
upgraded to the newest Ubuntu, which brought with it Lilypond version 2.10.5.
After converting the file with convert-ly, I tried running this new version of
Lilypond on it, but the computer just gets stuck at the end, saying that it is
"Preprocessing graphical objects...". I even let it grind away for a half an
hour just to see if it would finally come to an end, but it didn't. Cutting down
the file to just 7 pieces or so results in something that Lilypond *can*
actually compile, but it took about two minutes!

What went wrong in the step from version 2.6.3 to 2.10.2?

Sincerely,
Geoff Hemion