const string PC_CATEGORY = "_Tmp";
const string PC_NAME = "_Tmp";
 
if (!PerformanceCounterCategory.Exists(PC_CATEGORY))
{
    CounterCreationDataCollection data = new CounterCreationDataCollection();
    CounterCreationData counter = new CounterCreationData(PC_NAME, "", PerformanceCounterType.NumberOfItems32);
    var pcCategory = PerformanceCounterCategory.Create(PC_CATEGORY, "", PerformanceCounterCategoryType.MultiInstance, data);
 
    data.Add(counter);