opps i havent replyed in over a year :S
here is the description:
Performance boost(lockups/fps)
Get it here.
you have to copy all the audiofiles from cd2 to your harddrive and then overwrite some of the audiofiles with the ones included in this patch . This removes the radios which use a lot of memory(don't use this patch if you've got 384mb of ram or more)
Rudolf is the one who posted it:
http://www.gtaforums.com/index.php?showtopic=44030