Please check this document if you want to optimize the performance of the integration between SAP TM and SAP EM:
Integration of SAP TM and SAP EM - Optimizing the Performance
Summary:
Recently some new features have been introduced in the area of the data extraction for SAP EM in SAP TM. With these some new possibilities to optimize the performance are available. This document gives an overview of the several points which are relevant regarding the performance of the data extraction and gives some recommendations and best practices. It is highly recommended to follow the guidance given by this document.