Collecting situations in which routing is slow

[jbruechert]

I'll use this issue to collect examples of places with performance issues, in case someone has time to look at them / debug them.

• There is some bottleneck in the middle of the journey, were very little connections are available (Routing in areas with little data is very slow #443).
  Routing takes long because the time interval needs to be increased very much to find a connection.
• Lots of data is available. The actual routing step already takes long, before increasing the interval is even considered.
  This can be found for example in Paris.
  Example:
  • Paris Gare de Lyon -> Vincennes

[felixguendling]

Thank you! @mority is currently looking into this 🚀

[mlundblad]

Another example:

• Basel SBB → Milan C.Le

[vkrause]

Another example:

* Basel SBB → Milan C.Le

More observations on this one:

• Seems to affect anything on the south-bound Gotthard route, also shorter ones like e.g. Zürich -> Lugano.
• The opposite direction works.
• europe.motis-project.de is not affected despite having the same CH dataset, so this is possibly caused by some of the additional datasets in Transitous also covering that area?

[PureTryOut]

At which point is a route considered too long to care about? I've tried planning a route from Arnhem Centraal (the Netherlands) to Nürnberg Hbf (Germany) and it 504's.

[vkrause]

Lots of data is available. The actual routing step already takes long, before increasing the interval is even considered.
This can be found for example in Paris.
Example:

* Paris Gare de Lyon -> Vincennes

This also seems to be directional, e.g. Paris Montparnasse -> Toulouse Matabiau (direct TGV connection) fails outbound but works perfectly fine for the return trip.