Note: 1431798 has proved relevant in improving performance several times.
Each SAP Sourcing uses a number of Database connections which increases with each instance added as the sourcing application seeks to allocate and hold Database connections.
The standard values that affect this are as follows.
Within Note 1431798 it mentions the following formulas for the Database.
SESSIONS = 2 * PROCESSES
PROCESSES = #J2EE server processes = <max-connections> + PARALLEL_MAX_SERVERS + 40
The required increases are highlighted in BOLD for the Session and Processes settings.
This should prevent certain bottlenecks in database connections.