Please test this by adding a new conf file to ovirt-engine-dwhd.conf.d : DWH_JVM_ARGS="-Xms1g -Xmx1g" and restart dwh service. Please how this affects the resources utilization on a scale environment. Also this should not affect production environment so can be tested on an internal production environment. It can be tested on a 4.0 environment as well.
moving to VERIFIED for performance we have dependant bug