index.js

// Number of objects in the JSON (reduce it to 20 ... no much difference!!!)
const NUMBER_OF_ENTRIES = 5800;
const numbers = [...Array(NUMBER_OF_ENTRIES).keys()];

// Generating an arbitrary Array of objects w/o additional IDs (the "normal" version) 
const slowJSON = numbers.map(el => {
  return { id: el, value: String(Math.ceil(Math.random() * 1000000)) };
});

// Generating an arbitrary Object using additional ID's (a version optimized for the search cases we will have in the frontend)
const fastJSON = numbers.reduce((obj, el) => {
  return {
    ...obj,
    [el]: { id: el, value: String(Math.ceil(Math.random() * 1000000)) }
  };
}, {});

// Randomly generate an ID for an object to be selected
const selectable = Math.ceil(Math.random() * 5800);

// Timing the slow version
console.time("Array");
const result = slowJSON.filter(el => {
  return el.id === selectable;
});
console.timeEnd("Array");

// Timing the fast version
console.time("Object");
const result2 = fastJSON[selectable];
console.timeEnd("Object");

// Simple transform to turn the "fast" object structure into the "slow" one (what would have to be done on the JAVA side)
const transform = Object.keys(fastJSON).map(id => fastJSON[id]);
// console.log("Transform: ", transform);