The ability to use multiple profiles introduced in #450 changed the way we now access cost values. Instead of a single matrix lookup previously, we now have a ponderation with a vehicle-dependent speed factor happening in Vehicle::Cost:

This is a price we have to pay for the sake of a much bigger flexibility in cost evaluation. The downside is that this also means a computing time increase for single-profile instances even with unused vehicle speed_factor (see #450 (comment)).

I've tried to make this as efficient as possible, in particular by providing the Vehicle::Cost implementation in header file to allow the compiler to perform some optimizations in other units. I wonder if there is more to it and if we could improve the structures or the layout to further reduce the increase. I guess this would call for some profiling to get a clearer view of what are the most expensive bits here.