Put a 1MB string at the lowest level of a 700-level deep object, then serialize and deserialize it, shows node-mongodb-native dbson deserialization performance issue.

test_deep_object.js

require.paths.unshift("../../lib");

var sys = require('sys'),
  Buffer = require('buffer').Buffer,
  BSON = require('./bson').BSON,
  Buffer = require('buffer').Buffer,
  BSONJS = require('mongodb/bson/bson').BSON,
  BinaryParser = require('mongodb/bson/binary_parser').BinaryParser,
  Long = require('mongodb/goog/math/long').Long,
  ObjectID = require('mongodb/bson/bson').ObjectID,
  Binary = require('mongodb/bson/bson').Binary,
  Code = require('mongodb/bson/bson').Code,
  DBRef = require('mongodb/bson/bson').DBRef,
  assert = require('assert');

sys.puts("=== EXCEUTING TEST_DEEP_OBJ ===");

// Simple serialization and deserialization for an Object
var dt = new Date();
var oBig = {o: {}};

function aString(length) {
  var str = '';
  for (var i = 0; i < length; i++) {
    str += 'a';
  }
  return str;
}
var x = aString(1000 * 1000);

var o = oBig.o;
for (var i = 0; i < 700; i++)
{
  if (i == 699) o.x = x;
  o.o = {};
  o = o.o;
}

console.log(['About to serialize', (new Date()).getTime() - dt.getTime()]);
var big = BSON.serialize(oBig);
console.log(['Serialized', (new Date()).getTime() - dt.getTime()]);
BSON.deserialize(big);
console.log(['Deserialized', (new Date()).getTime() - dt.getTime()]);