Since Flex 4 beta I stopped using Repeaters so I cannot tell you an exact answer but maybe you should think about using DataGroup. I didn't had direct comparison of two equal applications, one that uses Repeaters and one with DataGroup. DataGroup is more leightweight component than Repeater. I think it is practicly the simpliest group component in Flex 4.
Also, maybe you should consider this article. It talks about using virtualization and item renderer memory management in spark components.
I hope I gave you something to think about
yes helpful info . i will go through it.