C# List vs IEnumerable performance question

Question

Hi suppose these 2 methods:

private List GetProviderForType(Type type)
        {
            List returnValue = new         


        

Answer 1

An important part of this question is "how big is the data"? How many rows...

For small amounts of data, list is fine - it will take negligible time to allocate a big enough list, and it won't resize many times (none, if you can tell it how big to be in advance).

However, this doesn't scale to huge data volumes; it seems unlikely that your provider supports thousands of interfaces, so I wouldn't say it is necessary to go to this model - but it won't hurt hugely.

Of course, you can use LINQ, too:

return from provider in _objectProviders
       where provider.Key.IsAssignableFrom(type) ...
       select provider.Value;

This is also the deferred yield approach under the covers...