This might be completely unrelated, but I gained much in performance when I migrated from child reports in 2.11 to components in v3.
Most of the gain was due to my misuse of child reports. In my calls to the child reports I added data, sometimes quite a lot of data. I didn't realise that the calls to child reports would copy all the data. This was very taxing on the memory on my server, especially when multiple large reports were rendered.
Even if you are not misusing child reports, as I did, I think components are a much nicer concept.
Jan, what do you mean by "disabling the ARIA"? Where can I do this?