__LIGHTHOUSE_JSON__ analysis script

lhjson.js

(function() {

function strSize(obj) {
    const string = JSON.stringify(obj);
    return string ? string.length : 0;
}

const lhj = __LIGHTHOUSE_JSON__;
const fullSize = strSize(lhj);
const maxLevels = 5;

function analyzeKeys(obj, level = 0) {

 Object.keys(obj)
  .map(field => ({
      name: field,
      size: strSize(obj[field])
  }))
  .sort((a, b) => b.size - a.size)
  .forEach(field => {
    const percentage = Math.round((field.size * 100)/fullSize);
    const value = field.name === 'name' && (typeof obj[field.name] === 'string') ? ` ${obj[field.name]}` : '';
    const label = `${' '.repeat(level)}↪ ${field.name}:${value} ${percentage}%`;

    if (percentage > 0 && level < maxLevels) {
        console.groupCollapsed(label);
        analyzeKeys(obj[field.name], level + 1);
        console.groupEnd();
    } else {
        console.log(label);
    }
  });
}

analyzeKeys(lhj);

})();

Run in the console of the raport page to get a following breakdown of __LIGHTHOUSE_JSON__: