与2.4相比，Mongodb 2.6中的插入速度较慢

Question

我在MongoDB 2.6中运行此插件，其时间是MongoDB 2.4的两倍。

people = ["Marc", "Bill", "George", "Eliot", "Matt", "Trey", "Tracy", "Greg", "Steve",   "Kristina", "Katie", "Jeff"];
for(var i=0; i<1000000; i++){
    name = people[Math.floor(Math.random()*people.length)];
    user_id = i;
    boolean = [true, false][Math.floor(Math.random()*2)];
    added_at = new Date();
    number = Math.floor(Math.random()*10001);
    db.test_collection.save( {"name":name, "user_id":user_id, "boolean": boolean, "added_at":added_at, "number":number });
    db.getLastError();
}

MongoDB 2.4用了7分钟，MongoDB 2.6用了14分钟。