Is there a way to optimize a triple nested loop for accessing and object

Question

I need to build a application to extract data from multiple JSON-Files and store it into a Database.

The File looks like this and parsed results in a highly nested object.

To explain, i need to go through all Items in the "Mandanten" Object and for each key i need to go into the "Saison" Objects and get again a list of key value pairs, which is needed to go into the "CompetitionTypes" Object and there i set the "Mandanten"-key as well as the "Saison"-key and get another list of key value pairs. All these keys are now needed to download another file and do a similar process again.

My solution to extract the data resulted in a triple nested loop and very ineffective code, which is shown below

I implemented a solution which was coded very fast and is working, but it looks very ugly for me. I want to refactor this now to a better and more important faster, because when i run it the last time it needed 25min to run.

Is there a way to avoid these triple nested loop or any other ways to make it faster?

function loadKinds() {
  let wam = undefined;
  try {
    wam = JSON.parse(wamString);
  } catch (error) {
    console.log(error);
  }
  console.log(wam)
  const mandanten = wam.Mandanten;
  const saisons = wam.Saisons;
  const competitons = wam.CompetitionTypes;

  const mandanten_map = new Map();
  const saisons_map = new Map();
  const competitonsTypes_map = new Map();
  const combinations = [];


  Object.keys(mandanten).forEach(key => {
    mandanten_map.set(formatKey(key), mandanten[key]);
    const formatted_mandant = formatKey(key);

    Object.keys(saisons[formatted_mandant]).forEach(key => {
      saisons_map.set(formatKey(key), saisons[formatted_mandant][key]);
      const formatted_saison = formatKey(key);

      Object.keys(competitons[formatted_mandant][formatted_saison]).forEach(key => {
        competitonsTypes_map.set(formatKey(key), competitons[formatted_mandant][formatted_saison][key]);
        combinations.push([formatted_mandant, formatted_saison, formatKey(key)]);
      });
    });
  });

  return ({
    mandanten: Array.from(mandanten_map),
    saisons: Array.from(saisons_map),
    competition_types: Array.from(competitonsTypes_map),
    competitions: combinations
  });
}


function formatKey(key) {
  return key.replace('_', '');
}
loadKinds();

<script>
  const wamString = `{
  "currentSaison": "2223",
  "defaultCompetitionType": "1",
  "Mandanten": {
    "_21": "Westfalen",
    "_22": "Niederrhein",
    "_23": "Mittelrhein",
    "_31": "Bayern"
  },
  "Saisons": {
    "21": {
      "_2324": "23/24",
      "_2223": "22/23",
      "_2122": "21/22"
    },
    "22": {
      "_2223": "22/23",
      "_2122": "21/22",
      "_2021": "20/21"
    },
    "23": {
      "_2223": "22/23",
      "_2122": "21/22",
      "_2021": "20/21"
    },
    "31": {
      "_2223": "22/23",
      "_2122": "21/22",
      "_2021": "20/21"
    }
  },
  "CompetitionTypes": {
    "21": {
      "2122": {
        "_1": "Meisterschaften",
        "_305": "Spielnachmittage",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb"
      },
      "2223": {
        "_1": "Meisterschaften",
        "_305": "Spielnachmittage",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb",
        "_2": "Hallenturniere"
      },
      "2324": {
        "_300": "Turniere"
      }
    },
    "22": {
      "2021": {
        "_1": "Meisterschaften",
        "_305": "Spielnachmittage",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb"
      },
      "2122": {
        "_1": "Meisterschaften",
        "_305": "Spielnachmittage",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb"
      },
      "2223": {
        "_1": "Meisterschaften",
        "_305": "Spielnachmittage",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb",
        "_2": "Hallenturniere"
      }
    },
    "23": {
      "2021": {
        "_1": "Meisterschaften",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb"
      },
      "2122": {
        "_1": "Meisterschaften",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb"
      },
      "2223": {
        "_1": "Meisterschaften",
        "_308": "Pokale",
        "_300": "Turniere",
        "_70": "Freundschaftsspiele",
        "_11": "Futsal-Ligabetrieb",
        "_2": "Hallenturniere"
      },
      "31": {
        "2021": {
          "_1": "Meisterschaften",
          "_305": "Spielnachmittage",
          "_308": "Pokale",
          "_300": "Turniere",
          "_70": "Freundschaftsspiele",
          "_11": "Futsal-Ligabetrieb",
          "_2": "Hallenturniere"
        },
        "2122": {
          "_1": "Meisterschaften",
          "_305": "Spielnachmittage",
          "_308": "Pokale",
          "_300": "Turniere",
          "_70": "Freundschaftsspiele",
          "_11": "Futsal-Ligabetrieb",
          "_2": "Hallenturniere"
        },
        "2223": {
          "_1": "Meisterschaften",
          "_305": "Spielnachmittage",
          "_308": "Pokale",
          "_300": "Turniere",
          "_70": "Freundschaftsspiele",
          "_11": "Futsal-Ligabetrieb",
          "_2": "Hallenturniere"
        }
      }
    }
  }
}

`
</script>