Here is the code:

using System;
using System.Collections;
using System.Reflection;

namespace ReflectionExample
{
	public class ReflectionCache
	{
		// singleton
		public static ReflectionCache Instance = new ReflectionCache();

		private Hashtable list = new Hashtable();

		private ReflectionCache()
		{
		}

		// get methods for specified type
		public MethodInfo[] GetMethods(Type type)
		{
			if(!list.ContainsKey(type))
			{
				// type was not found, so call reflection and store the result
				// in the list for next time
				list[type] = type.GetMethods();
			}

			// serve request from list
			return (MethodInfo[])list[type];
		}
	}
}

using System;
using System.Collections;
using System.Reflection;

namespace ReflectionExample
{
	class Class1
	{
		[STAThread]
		static void Main(string[] args)
		{
			Console.WriteLine("ReflectionExample started...\n");

			testUncached();
			testCached();

			Console.WriteLine("\npress any key to exit...");
			Console.ReadLine();
		}

		private static int loops = 100000;
		private static DateTime start;
		private static DateTime stop;
		private static TimeSpan diff;

		private static Type[] testTypes = new Type[] 
			{ typeof(ArrayList), typeof(SortedList), typeof(Hashtable) };

		private static void testUncached()
		{
			start = DateTime.Now;

			for(int i=0; i<loops; i++)
			{
				testTypes[0].GetMethods();
				testTypes[1].GetMethods();
				testTypes[2].GetMethods();
			}

			stop = DateTime.Now;
			diff = stop - start;

			Console.WriteLine("uncached, elapsed time: " + diff.ToString());
		}

		private static void testCached()
		{
			start = DateTime.Now;

			for(int i=0; i<loops; i++)
			{
				ReflectionCache.Instance.GetMethods(testTypes[0]);
				ReflectionCache.Instance.GetMethods(testTypes[1]);
				ReflectionCache.Instance.GetMethods(testTypes[2]);
			}

			stop = DateTime.Now;
			diff = stop - start;

			Console.WriteLine("cached, elapsed time: " + diff.ToString());
		}
	}
}