Lately, I've heard many complaints about horizontal scrolling performance in DataGrid. Vertical scrolling has been optimized, but horizontal has not. I found a bit of time to put together how to subclass DataGrid and try to optimize horizontal scrolling. I'm sure there's bugs and I don't know if I'll have time to fix them and the usual caveats apply.
Hope it helps. It should work with any Flex 3 SDK version.
In the example, the top DataGrid is not optimized, the bottom one is. Make the screen bigger and you'll start to see and feel the difference.
