static readonly ConcurrentDictionary<string, Tuple<DateTime, PerformanceCounterCategory, InstanceDataCollectionCollection>> cache = new ConcurrentDictionary<string, Tuple<DateTime, PerformanceCounterCategory, InstanceDataCollectionCollection>>();

        private static string FindProcessInstance1(int pid, IEnumerable<string> instances, string categoryName, string counterName)
        {
            Tuple<DateTime, PerformanceCounterCategory, InstanceDataCollectionCollection> cached;

            DateTime utcNow = DateTime.UtcNow;

            InstanceDataCollectionCollection result = null;

            PerformanceCounterCategory category = null;

            if (cache.TryGetValue(categoryName, out cached))
            {
                category = cached.Item2;

                if (cached.Item1 < utcNow)
                {
                    result = cached.Item3;
                }
            }

            if (result == null)
            {
                if (category == null)
                {
                    category = new PerformanceCounterCategory(categoryName);
                }

                result = category.ReadCategory();

                cache.TryAdd(categoryName, new Tuple<DateTime, PerformanceCounterCategory, InstanceDataCollectionCollection>(utcNow.AddMinutes(1), category, result));
            }

            InstanceDataCollection counters = result[counterName];

            if (counters != null)
            {
                foreach (string i in instances)
                {
                    InstanceData instance = counters[i];

                    if ((instance != null) && (pid == instance.RawValue))
                    {
                        return i;
                    }
                }
            }

            return null;
        }