Having many documents in archive does not help. If you do not have thrascan cleaner, you can use some JS scripting for deleting some batches on it. By the way, the problem may be related with an application that intensively deletes documents, leaving them in Thrascan (with sys:temporary aspect you can delete without passing through trashcan).
Re: Reduce PostGreSQL DataBase size. Increase more than 1 GB/day.
Sometimes trashcan is opening without errors and I can delete a couple of documents. But I cannot understand why one time is open another time is not open - return error. May be it is related with database load I don't know.
In next days will do full vacuum, I hope this will help.
In parallel I have increased Read time out for alfresco, I hope increased time out also will help. Will see : ).
I'm an admin not dev person. Can do bash scripts but cannot do JS scripts : ).