We recently worked on some performance enhancements for the processes in SAP OER. I have created a consulting note, that keeps track of all notes that have been and will be released in this area. I will keep you updated here, every time new notes are available and the consulting note is updated. And I will start today 
10.02.2014 : New consulting note 1974465 (Performance optimization for SAP OER) is available
-> new notes available mainly to optimize the processing of EPCIS messages (partly available down to EM 7.0, partly only for EM 9.0)
Cheers, Daniel