Is there a benefit of using IsDefined over GetCustomAttributes

Question

Consider the case where an assembly contains one or more types attributed with a custom attribute MyAttribute and you need to get a list of these types. Is there any benefit of using IsDefined vs. GetCustomAttributes aside from the more compact syntax? Does one expose/hide something that the other doesn't? Is one more efficient than the other?

Here is a code sample demonstrating each usage:

Assembly assembly = ...
var typesWithMyAttributeFromIsDefined = 
        from type in assembly.GetTypes()
        where type.IsDefined(typeof(MyAttribute), false)
        select type;

var typesWithMyAttributeFromGetCustomAttributes = 
        from type in assembly.GetTypes()
        let attributes = type.GetCustomAttributes(typeof(MyAttribute), false)
        where attributes != null && attributes.Length > 0
        select type;

Answer 1

Done a quick test with the two methods and it seems IsDefined is a lot faster than GetCustomAttributes

200000 iterations

IsDefined average Ticks = 54
GetCustomAttributes average Ticks = 114

Hope this helps :)

Answer 2

As Saddam demonstrates, IsDefined is more efficient than GetCustomAttributes. That's to be expected.

As documented here, applying attribute MyAttribute to class MyClass is conceptually equivalent to creating a MyAttribute instance. However, the instantiation does not actually occur unless MyClass is queried for attributes as with GetCustomAttributes.

IsDefined, on the other hand, does not instantiate MyAttribute.