So, think about it like this:

Now, whenever you complete a chore, you have to run an update query. However, when you load chores from the database you no longer need to sort them in ruby. This means you are executing the logic for determining when the chore is next due in only one spot instead of in (potentially) hundreds/thousands.

So, updating will be computationally more expensive, but reading will be computationally less expensive. If we write more than we read, we may not want to store the due_date in the database. If we read more than we write, we will want to store the due_date in the database.

Re: How much faster? Well... That's a harder question. You'd have to benchmark both and decide for yourself.