FM performance tuning

Hi,

  I am using FM  BAPI_CUSTOMERCONTRACT_CHANGE and FM  SD_SALES_BILLINGPLAN_CHANGE,but while executing its taking almost 20 minutes to execute each record,so i did sql trace and i found its taking more time to fetch records in coes table in include LKAOVF16 while executing sql stmt to fetch records ( almost 15 minutes ),but when i use se11 or just coding i can fetch in about 10 seconds.

Any idea to tune FM.( memory buffering anything is really appreciated ).

Cheers,

Vj