This article (here) from LogicMonitor provides some interesting performance counters to review to isolate potential SQL Server performance issues. The performance counter charts are from the LogicMonitor monitoring tool, however, the same counters can be captured using your favourite performance counter capture tool.
On numerous occasions I’ve had customers complain about intermittent SQL Server performance only to find that the root cause was not the workload generated by the SQL Server VM but that the VMware environment was oversubscribed and was not providing sufficient CPU resources to the SQL Server when required.
Reviewing the deltas of Wait Statistics and Database File IO gives you a better indication of what is happening now on your SQL Server now and are not skewed by the historical accumulated values.