My clients (on 2.2 Ghz P4s) are running into script timeouts while the grid is building. It's a relatively small dataset with only about 450 rows with 5 column wide. Are their any speed/efficiency enhancements with the new release?
Is the table hidden (display:none) when building? IE has _major_ performance issues with this, and it's not something I can work around in Javascript unfortunately. Other than that - I'm not aware of anything which should be taking a table so long to render! Can you post a link?
The only thing that does make datatables slow is in fnAddData the function _fnBuildSearchArray
if you don't require filtering, you could add a boolean to check whether you want to be able to apply filters or not, that increases the addition of data onto the table ten-fold i'd say.