I know there are already some questions on this topic on the site...
I am just trying to understand if it's safe to use ASP.NET Profile Provider with a website with huge traffic?
The way I see it, it's laid out inefficiently. You store property name (which is a string) and property value (which is a string too). If you are just trying to store even age in the profile, you are unnecessarily storing the string "age" in the database over and over whereas with a self-created table, you could just add a column titled age, and no redundancy?
(I am just trying to make sure I am not missing something about it, because I am fairly new to it.)
The profile provider uses an EAV (Entity-Attribute-Value) design deliberately, because profiles in general very commonly have a sparsely populated schema - that is, there are many potential attributes, but only a few will be used for a given single entity, and the few that are used varies widely from one entity to the next.
Let's use a totally arbitrary example - let's say only one in 10 of your users want to provide their age. Making that a column now seems more like a waste, no?
But what if your application makes age mandatory? OK, that column gets populated for everyone. But what if you need to make a note in the profile "user doesn't want to see this obscure dialog anymore". Do you really want a column for every single dialog in your application whether a user wants to see it? Probably not. When you get into the little one-off details of an application of any significant scope, EAV actually becomes the more economical choice.
In the general, it scales quite well (far better than you probably think). In the specific, it doesn't matter - as always, use what works and fix performance problems when they come up. Whatever the scalability limitations of the profile provider are, you'll know when you hit them. I guarantee two things - (1) you'll have to fix a lot of other performance problems you didn't expect before you have to fix that; and (2) if your site is getting enough traffic to break the profile provider, it's a good problem to have.