Is there a better, more efficient way than Dictionary(Of Tuple(), MyClass)?
If you're stuck with Tuple&lt;T1,T2&gt; as a key, you want to provide an IEqualityComparer&lt;Tuple&lt;T1,T2&gt;&gt; implementation in the constructor of your dictionary.

If you can change the TKey type, you might want to provide a custom class that implements IEquatable&lt;T&gt;.

The problem with the current code is that comparison between keys of type Tuple&lt;string, string&gt; is not efficient.