I have recently started using ReorderableList element. I've had to implement some kind of 'list of lists' and would like to share my ideas about improvements. The API itself is mostly fine, but there are numerous bugs and inconsistencies.

Recently I've had to implement a very high performance component that required treating elements of an array differently based on their type. All the elements were put into a list of base types, and the method operating on the elements had to behave completely differently based on these types. I have made performance measurements in all the relevant cases. Code and numbers inside the article.