Extended collection

Hi,
How to explain......

I have some data and i have to export them in txt files in a certain format.

I use a collection to store the lines i have to put in my file.

The problem is that after adding quite a lot of items, my algorithm sucks.

To improve this, i need to find the index of an item from its key and vice versa, then i think could use the nodes collection of treeview. But i heard that it has some drawbacks.

So my question is:
Can i use the treeview nodes collection without problems and with good performance, if no do i must extend the collection class or is it already done? ;)

thx