It is often said don't optimize too early. I try very hard to keep to that, and I do mean very hard. In the project I am working on now we have a basically working implementation (although some functionality is still to code, it is on the edges - this probably counts as too early - oh dear). We have a rather complicated setup which I don't have the time to go into here but at its simplest it is the age old client-server relationship and involves a lot of database (Oracle via DBD::Oracle) access. The client in this case is really a daemon process receiving work to process and either processing it or passing it on to another server to be queued and worked on later.
I've been working on 1.22 doesn't compile on 64 bit systems with unixODBC on and off for a few days. Boy, this is tiresome (no reflection on the poster of this rt).
Today a long standing Easysoft customer upgraded from DBD::ODBC 1.13 to 1.21 and their scripts stopped working properly :-( It appears they use the ping method to detect whether the connection handle is connected to the database and since upgrading to 1.21 they are getting DBD::ODBC::db ping failed: Cannot allocate statement when disconnected from the database at ./xxx.pl line 11 when calling the ping method after a disconnect.