Description of problem:
1st removal time of the RHV provider is quite large: 
GR (Graph Refresh) OFF: 17 min,
and for GR ON it's even larger GR ON: 41 min.

Testing environment details:
2 CFME-5.9.3 machines (Memory 8G, 4 cores) (in US)::
   1. With Graph refresh OFF (default)
   2. With Graph refresh ON.

Scale RHV-4.2.3.5-0.1.el7 (in RDU):
   b01-h21-r620.rhev.openstack.engineering.redhat.com
   Clusters	 4
   Hosts	 403
   Datastores	 6
   Virtual Machines 4059
   Templates 13

Test results:
   Graph refresh OFF:
   1st removal 17 min
   2nd removal 1 min

   Graph refresh ON:
   1st removal 41 min
   2nd removal 1 min

Notes:
* Both RHV & CFME located in the US, so these tests are with no latency.
* Removal time is taken from the CFME UI tasks page, task: "Destroying  
  ManageIQ::Providers::Redhat::InfraManager with id: "

Version-Release number of selected component (if applicable):
CFME-5.9.3
RHV-4.2.3.5-0.1.el7