gistfile1.txt

var record = {
	id: idgen(20) ,
	data: {
		ip: parts[0],
		agent: parts[1],
		url: parts[2],
		referrer: parts[3],
		mobile: mobile
	}
};
userRecords.push(record);

...

db.on('ready', function () {
	userRecords.forEach(function(record,index,array) {
		db.put(record.id,record.data, function(err) {
			if(err) 
				console.log(clc.redBright.bold('Error inserting user record: ') + err);
			if (index == array.length-1)
				console.timeEnd('user-leveldb-write');	
		});
	});

})

500 records work
500K records does not.