Top-N Display Tab
View Performance Monitor - Top-N-Display page
The Top-N Display tab on the Preferences window for the Performance Monitor is for determining the percent of each statistics that is retrieved from the monitoring tables.
To select only the top statistics
Select the button on the left for the statistics information and fill in the values on the right for each individual statistic.
Please reference the Adaptive Server Performance and Tuning: Monitor and Analyzing manual for the meaning of each statistic.