Response time is high

Hi,

we have a enviroment of central instance, database instance, 2 dialog instances.

database instance and 2 dialog instances are a part of load distrubution.

i have seen that most the of the times central insance response time is high.

i have checked in ST06 (CPU, Memory Utilization) are normal.

i have checked the ST03N also but i cannot able to find any reason.

please help me to analyse the root cause of hish response time.

thanks

Bala.