Hey Alex, I know, it's hard to believe -- but I guess you'll just have to trust me on this one ;) I've made this same renderer about 10 times and spent a good 40-50 hours trying to improve the performance -- even going so far as removing all logic from it at times. It's not the renderer itself that's causing the majority of the performance hit.
I'd love to post some examples... but unfortunately that nasty NDA thing prevents me from showing the meat of it. If I get some time, I'll be sure to post some samples on my blog and link them on this list. The moral of the story I've learned is that if you're building a complicated data table, Flex/Flash is not the route to go. HTML/Javascript would have been a far better solution at this point.
