You need to set databaseQueryTimeout (http://sdk.episerver.com/library/cms5/html/P_EPiServer_Configuration_Settings_DatabaseQueryTimeout.htm) in siteSettings.
And you can also set debug to true in web.config to remove the application timeout.
to siteSettings and it worked like a charm!
The database way is to run editdDleteChilds like in this thread:
I have the following scenario:
My question is: How can I resolve this failure of emptying the Recycle Bin?
According to myself 525 pages, along with versions, aren't that many...