Populate a list from user Profile Sync

Hi,

i Need to get details from the user profile sync and populate a list. (User and Birthday)

Here is some more background if there might be a different way to do this:

We had a developer where i work who wrote a Web Part that got a birthday list directly out of the User Profile Sync but it slowed down the site to much and it was disabled.

The developer has since resigned and there is no documentation on how the web part work.

Then after that the idea was to populate a list every now and then and get the information for the web part from a list.

At this point im forgetting about the web part and trying to get different ways on how to do this.

Maybe populate a list and then set a filter or something on the list.

There is quite a few thousand users in the environment so getting the details from the user Profile sync every-time someone opens a site with the web part on it wont work.

 Thanks in Advance