Improve performance of flex routing

[leonardehrenfried]

The following query:

query{
  plan(
    date: "2021-06-16"
    time: "22:30"
    from: { lat:  48.6226, lon: 8.8879 }
    to: { lat: 48.5755, lon: 8.8795 }
    transportModes: [
      { mode: RAIL },
      { mode: FLEX, qualifier: EGRESS },
      { mode: FLEX, qualifier: DIRECT },
      { mode: WALK },
    ],
    carReluctance: 10
  ) {
    itineraries {
      legs {
        mode
        rentedBike
        distance
        startTime
        endTime
        dropOffBookingInfo {
          message
        }
        pickupBookingInfo {
          message
          contactInfo {
            phoneNumber
            infoUrl
            bookingUrl
          }
        }
        dropOffBookingInfo {
          message
        }
        route {
          url
          mode
          shortName
          type
        }
        trip {
          gtfsId
          tripShortName
          
        }
        from {
          name
          bikeRentalStation {
            name
            id
          }
          
        }
        to {
          name
          bikeRentalStation {
            name
            id
          }
        }
      }
    }
  }
}

takes around 7 seconds.

Please investigate if this can be made quicker.