Storing complex objects in memory in a web application?

For each user in my nodejs application, I need to store objects that look something like this (I'm using JSON merely to represent the data):

{
    id: 12345,
    name: "John Smith",
    count: 5,
    status: 0,
    msgs: ["message1", "message2", "message3"],
        title: "this is a title"
}

My options so far -

• Put them in mongoDB. This doesn't seem like a good idea since I'll be reading and writing to them very often (every few minutes).

• Put them in a Redis store. This seems OK, but I cannot create complex objects directly. Serializing/Deserializing each object seems painful.

What's the best way to store them? What are my other options?