You can set the number of partitions.
You can use use wpfAdmin.bat|wpfadmin setPartitionCount PARTITION_COUNT --id PMI_SUBSCRIPTION_ID to set the partition count for one PMI subscription. You can also use Java code, jacl script, or jython script to get the com.ibm.websphere.wpf.jmx.WPFJMX MBean instance, and change the partition count through the MBean.