Performance enhancements for #380 fix.

src/MvcSiteMapProvider/MvcSiteMapProvider/Collections/Specialized/NameValueCollectionExtensions.cs

@@ -17,6 +17,7 @@ public static void AddWithCaseCorrection(this NameValueCollection nameValueColle
                 {
                     // Add item with corrected case key
                     nameValueCollection.Add(item, value);
+                    break;
                 }
             }
         }

src/MvcSiteMapProvider/MvcSiteMapProvider/RequestCacheableSiteMapNode.cs

@@ -1,6 +1,9 @@
 using System;
 using System.Text;
 using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Linq;
+using System.Web;
 using MvcSiteMapProvider.Caching;
 using MvcSiteMapProvider.Globalization;
 using MvcSiteMapProvider.Web.Mvc;
@@ -167,6 +170,27 @@ public override string Route
             set { this.SetCachedOrMemberValue<string>(x => base.Route = x, "Route", value); }
         }
 
+        protected override NameValueCollection GetCaseCorrectedQueryString(HttpContextBase httpContext)
+        {
+            // This method is called twice per node only in the case where there are 
+            // preserved route parameters, so the memory trade-off is only worth it if
+            // we have some configured.
+            if (this.PreservedRouteParameters.Any())
+            {
+                var key = this.GetCacheKey("GetCaseCorrectedQueryString_" + httpContext.Request.Url.Query);
+                var result = this.requestCache.GetValue<NameValueCollection>(key);
+                if (result == null)
+                {
+                    result = base.GetCaseCorrectedQueryString(httpContext);
+                    this.requestCache.SetValue<NameValueCollection>(key, result);
+                }
+
+                return result;
+            }
+
+            return base.GetCaseCorrectedQueryString(httpContext);
+        }
+
         protected override bool AreRouteParametersPreserved
         {
             get 

src/MvcSiteMapProvider/MvcSiteMapProvider/SiteMapNode.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Linq;
 using System.Web;
 using System.Web.Mvc;
 using System.Web.Routing;
@@ -645,7 +646,7 @@ protected virtual void PreserveRouteParameters()
 
         /// <summary>
         /// Gets a <see cref="T:System.Collections.Specialized.NameValueCollection"/> containing the query string
-        /// key value pairs for the passed in HTTP context. The casing of the keys corrected to be the same as the values that are 
+        /// key value pairs for the passed in HTTP context. The casing of the keys corrected to be the same case as the values that are 
         /// configured either in the <see cref="P:RouteValues"/> dictionary or the <see cref="P:PreservedRouteParameters"/> collection.
         /// </summary>
         /// <param name="httpContext">The HTTP context.</param>
@@ -656,9 +657,10 @@ protected virtual NameValueCollection GetCaseCorrectedQueryString(HttpContextBas
             var queryStringValues = httpContext.Request.QueryString;
             // Note: we must use the configured route values, rather than the RouteValue property to avoid an
             // infinite loop.
-            var caseInsensitiveRouteKeys = new HashSet<string>(this.routeValues.Keys, StringComparer.InvariantCultureIgnoreCase);
+            var routeKeys = this.routeValues.Keys.ToArray();
+            var caseInsensitiveRouteKeys = new HashSet<string>(routeKeys, StringComparer.InvariantCultureIgnoreCase);
             var caseInsensitivePreservedRouteParameters = new HashSet<string>(this.PreservedRouteParameters, StringComparer.InvariantCultureIgnoreCase);
-            var result = new NameValueCollection();
+            var result = new NameValueCollection(queryStringValues.Count);
 
             foreach (var key in queryStringValues.AllKeys)
             {
@@ -667,11 +669,11 @@ protected virtual NameValueCollection GetCaseCorrectedQueryString(HttpContextBas
                 {
                     if (caseInsensitivePreservedRouteParameters.Contains(key))
                     {
-                        result.AddWithCaseCorrection(key, queryStringValues[key], caseInsensitivePreservedRouteParameters);
+                        result.AddWithCaseCorrection(key, queryStringValues[key], this.PreservedRouteParameters);
                     }
                     else if (caseInsensitiveRouteKeys.Contains(key))
                     {
-                        result.AddWithCaseCorrection(key, queryStringValues[key], caseInsensitiveRouteKeys);
+                        result.AddWithCaseCorrection(key, queryStringValues[key], routeKeys);
                     }
                     else
                     {