How to measure a perfomance of SQL Server database?
I/O (hardware) bottlenecks are absent since the SQL Server runs on a virtual rack having 
  plenty of physical resources under it.


Let's get this straight:


Most virtualization is pathetic - not even low, pathetic - on the IO side.
"having plenty" means nothing unless you qantify there is no IO problem.


At the end, come up with the metcis you need to measure, and find the bottlenexks. But starting with "virtual rack has no IO issues" will give you smiles from most people using virtualization.