The graph is currently loaded from the osm.pbf file using osm4routing: https://github.com/Tristramg/roads-from-nd/blob/master/src/main.rs#L68 ; so the same parsing work is done on each execution.

It could be nice to be able to write down the node and edges files produced by osm4routing. The next execution with different parameters or start node might then get a significant speed-up by only loading the graph in memory from those files.

Another way of doing this would be to just provide an options to load from those files rather than from osm.pbf (and let users generates the files themselves using osm4routing).

From an Ubuntu box 16.04 x64, I've installed rust with instructions from https://www.rust-lang.org/fr/downloads.html

curl -sSf https://static.rust-lang.org/rustup.sh | sh

Then, I installed roads-from-nd with

# sudo was required
sudo cargo install roads-from-nd

Then, I've taken Geofabrik export with

wget http://download.geofabrik.de/europe/france/pays-de-la-loire-latest.osm.pbf

Following your recipe, I've tried

roads-from-nd pays-de-la-loire-latest.osm.pbf 314390639 out.pdf

where the node 314390639 is part of a way in "Pays de La Loire" e.g https://www.openstreetmap.org/node/314390639

At the end, I got the following output

Did I miss something in your recipe in French at https://www.codeursenliberté.fr/cartographie/routes_depuis/?