Any BigFix installation of a reasonable size will move from a colocated database to a remote database. It is entirely inappropriate for support to disavow remote databases. A helpful support engagement should include paths to discover root causes for horrid delays.
I suggest asking your sales/support reps about a health check. (Tagging: @jgo, @RhondaSTK_HCL )
Meanwhile, review the sizing/performance documentation.
(FWIW, our installation is entirely virtual, on VMWare in an on-site datacenter: root server, database, relays, WebUI, etc. Everything. The database is on a dedicated SQL server. Inside the virtual environment, resource affiliation keeps the SQL server and root server colocated to the same physical host. The backline storage is… I dunno. Something nifty. I rarely need to get involved that deeply.)