at the time of slow experience of the performance
So this behaviour is not always!
Just check what are active during the slowness of system?
Check ST06 for utilization, Check SM66 for active jobs/sessions, Check ST04 for expensive SQL statements, Check DB12 for active DB schedule jobs.
Once you got the clue, further investigation/tuning can be done.
Most of the times, I observe such slowness due to some high expensive SQL statements/bad program!
Regards,
Nick Loy