If your applications contains "EXEC CICS STARTBR" API and found application taking more time for execution, you can try rebinding the TXSeries supplied DB2 packages with "REOPT ALWAYS" as follows.
1) Connect to DB2 database
2) Rebind the CICS packages:
Go to /usr/lpp/cics/etc directory
Run the following command to rebind the CICS package with option REOPT ALWAYS/
# db2 bind @cics101.bndlst REOPT ALWAYS
# db2 bind @cics102.bndlst REOPT ALWAYS
# db2 bind @cics37.bndlst REOPT ALWAYS
# db2 bind @cics82.bndlst REOPT ALWAYS
This might speed up the execution time for "EXEC CICS STARTBR" API.
Note: The performance improvement may vary from case to case depend on the design of application and also the other DB2 configuration.