Jax made a great object called the List & Set II Object, but it was mainly for mathematical purposes and not an actual list object replacement. The List object itself is slow when you need to be fast because it, being a Windows control, likes to redraw when you modify it. Even when it is set to invisible, it still takes time to modify the list.
That is why I made the Internal List Object - it is much much faster than the List object and it has some the same features. It's in beta now because I want to find the issues before I finish the rest of it.
You can download the current Beta here: http://www.LB-Stuff.com/MMF2/Extensions/InternalList_BETA.zip
Make sure to check the example and see how the list object compares to this extension.
Please test it and let me know of any issues or missing features it may have.