function time(cmd, runs, runNumber, results, cb) {
	const start = process.hrtime();

	exec(
		cmd,
		{ maxBuffer: 64 * 1024 * 1024, silent: true },
		(code, stdout, stderr) => {
			const diff = process.hrtime(start),
				actual = diff[0] * 1e3 + diff[1] / 1e6; // ms

			if (code) {
				echo(`  Performance Run #${runNumber} failed.`);
				if (stdout) {
					echo(`STDOUT:\n${stdout}\n\n`);
				}

				if (stderr) {
					echo(`STDERR:\n${stderr}\n\n`);
				}
				return cb(null);
			}

			results.push(actual);
			echo(`  Performance Run #${runNumber}:  %dms`, actual);
			if (runs > 1) {
				return time(cmd, runs - 1, runNumber + 1, results, cb);
			}
			return cb(results);
		},
	);
}
Calculates the time for each run for performance
@param {string} cmd cmd
@param {number} runs Total number of runs to do
@param {number} runNumber Current run number
@param {number[]} results Collection results from each run
@param {TimeCallback} cb Function to call when everything is done
@returns {void} calls the cb with all the results
@private