prd_log4j.xml

<!-- PRDPERF Add This file appender  to output aggregated performance statistics -->
   <appender name="PerformanceFileAppender" class="org.apache.log4j.DailyRollingFileAppender">
     <param name="File" value="/home/pentaho/pentaho/server/biserver-ee/logs/prd-perfStats.log"/>
      <param name="Append" value="true"/>
      <!-- Rollover at midnight each day -->
      <param name="DatePattern" value="'.'yyyy-MM-dd"/>
     <layout class="org.apache.log4j.PatternLayout">
       <param name="ConversionPattern" value="%d{dd.MM.yyyy.HH.mm.ss.SSS}||%t||%m%n"/>
     </layout>
   </appender>

   <category name="org.pentaho.reporting.libraries.base.util.LoggingStopWatch" additivity="false">
     <priority value="DEBUG"/>
     <appender-ref ref="PerformanceFileAppender"/>
   </category>
   
<!-- also this in classic-engine.properties
org.pentaho.reporting.engine.classic.core.states.PerformanceMonitorContext=org.pentaho.reporting.platform.plugin.PluginPerfomanceMonitorContext
-->