Haven't run into that need, I doubt most sites have, so I don't have a ready answer for you. We typically only change the parts of the page that have data that

Haven't run into that need, I doubt most sites have, so I don't have a ready answer for you. We typically only change the parts of the page that have data that has actually changed, so DOM rendering performance hasn't been a difficult problem for us. I thought you meant scalability in terms of code size, or number of people working on it, or number of users.