Best approach?

[3slices]

I am looking for the best approach performance wise for the following situation:

My userlist is a datagrid with an ArrayCollection as dataprovider. The ArrayCollection holds all user items.
As I need to implement some custom sorting, on every user enter and exit there needs to be performed some extra sorting and filtering, before the ArrayCollection gets rebuild and reflect the new state.

On heavy usage with lots of user enters and exits this is getting quity heavy as every enter end exit performs a rebuild. From a performance view it would be recommended to pool the changes and perform a rebuild only once in a while. Also I see the chance that the nature of the event handling causes inaccurate data with multiple rebuilds manipulating the ArrayCollection at the same time.

So what would be the best approach to ensure accurate data and best performance?