we have a similar issue on our environment as well. Based on a conversation with the oracle rep, it was confirmed that the resolution to this issues was provided in 188.8.131.52 version.
We are just requesting our users to use CSV in case of download to keep the file size smaller but this is not an ideal solution and makes our business users very unhappy. But no solution yet on our side..
Thanks for your response.
The way we are working at the moment is :-
1. Ask users to download in .csv if they just need raw data
2. While storing/sending the .xls files we have asked them to save the file as a excel workbook
However no workaround could be achieved for the reports sent as excels by agents(clogging spaced in user's mailboxes) or actual download volume of the formatted excel reports (excel taking an awfully long time to open the files).
As you mentioned, I heard that this issue was fixed on 184.108.40.206. Since this version is released for more than a quarter now, I wondered if someone out there can confirm that this has happened really.