encrypttest.js

const {
	performance
} = require('perf_hooks');
const EthCrypto = require('eth-crypto');

const identity = EthCrypto.createIdentity();

function randomString(string_length) {
	var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
	//var string_length = 8;
	var randomstring = '';
	for (var i = 0; i < string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum, rnum + 1);
	}
	return randomstring;
}

const msg = randomString(100000);

performance.mark('A');
EthCrypto.encryptWithPublicKey(
	identity.publicKey,
	msg // message
).then((encrypted) => {
	performance.mark('B');
	performance.measure('A to B', 'A', 'B');

	console.log(encrypted);

	performance.mark('C');
	EthCrypto.decryptWithPrivateKey(
			identity.privateKey,
			encrypted)
		.then((message) => {
			performance.mark('D');
			performance.measure('C to D', 'C', 'D');

			console.log('message length ' + message.length);
			console.log('message encrypted. Duration ' + performance.getEntriesByName('A to B')[0].duration + ' ms');
			console.log('message decrypted. Duration ' + performance.getEntriesByName('C to D')[0].duration + ' ms');

		});
});

package.json

{
  "name": "encrypttest",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "eth-crypto": "^0.4.0",
    "perf_hooks": "0.0.1"
  }
}