example of IResultFilter and IActionFilter

RequestTimingFilter.cs

using System.Diagnostics;
using System.Web.Mvc;

namespace YourApp.Web.Infrastructure.Filters
{
	/// <summary>
	/// Filter to display the execution time of both the action and result
	/// </summary>
	public class RequestTimingFilter : IActionFilter, IResultFilter
	{
		private static Stopwatch GetTimer(ControllerContext context, string name)
		{
			var key = string.Format("__timer__{0}", name);
			if (context.HttpContext.Items.Contains(key))
			{
				return (Stopwatch)context.HttpContext.Items[key];
			}

			var result = new Stopwatch();
			context.HttpContext.Items[key] = result;
			return result;
		}

		/// <summary>
		///   Called before an action method executes.
		/// </summary>
		/// <param name = "filterContext">The filter context.</param>
		public void OnActionExecuting(ActionExecutingContext filterContext)
		{
			GetTimer(filterContext, "action").Start();
		}

		/// <summary>
		///   Called after the action method executes.
		/// </summary>
		/// <param name = "filterContext">The filter context.</param>
		public void OnActionExecuted(ActionExecutedContext filterContext)
		{
			GetTimer(filterContext, "action").Stop();
		}

		/// <summary>
		///   Called before an action result executes.
		/// </summary>
		/// <param name = "filterContext">The filter context.</param>
		public void OnResultExecuting(ResultExecutingContext filterContext)
		{
			GetTimer(filterContext, "render").Start();
		}

		/// <summary>
		/// Called after an action result executes.
		/// </summary>
		/// <param name = "filterContext">The filter context.</param>
		public void OnResultExecuted(ResultExecutedContext filterContext)
		{
			var renderTimer = GetTimer(filterContext, "render");
			renderTimer.Stop();

			var actionTimer = GetTimer(filterContext, "action");
			var response = filterContext.HttpContext.Response;

			if (response.ContentType == "text/html")
			{
				response.Write(
				  string.Format(
					"<div style='font-size: 70%; font-weight: bold; color: #888;'>Action '{0} :: {1}'<br /> Execute: {2}ms, Render: {3}ms.</div>",
					filterContext.RouteData.Values["controller"],
					filterContext.RouteData.Values["action"],
					actionTimer.ElapsedMilliseconds,
					renderTimer.ElapsedMilliseconds
					)
				  );
			}
		}
	}
}