We are facing exactly the same thing with graphs, we're using a custom canvas based solution but we found out it just isn't up to the task anymore when we need

We are facing exactly the same thing with graphs, we're using a custom canvas based solution but we found out it just isn't up to the task anymore when we need them to display lots and lots of data. Browser lockups are a result because it is just that Javascript intensive. We are looking at Flash solutions right now to solve that problem.