diff --git a/src/Http/Routing/src/Matching/DfaMatcher.cs b/src/Http/Routing/src/Matching/DfaMatcher.cs
index b39ca762a9..dc9a3a7b43 100644
--- a/src/Http/Routing/src/Matching/DfaMatcher.cs
+++ b/src/Http/Routing/src/Matching/DfaMatcher.cs
@@ -228,13 +228,14 @@ namespace Microsoft.AspNetCore.Routing.Matching
         {
             for (var i = 0; i < captures.Length; i++)
             {
-                var parameterName = captures[i].parameterName;
-                if (segments.Length > captures[i].segmentIndex)
+                (var parameterName, var segmentIndex, var slotIndex) = captures[i];
+                
+                if ((uint)segmentIndex < (uint)segments.Length)
                 {
-                    var segment = segments[captures[i].segmentIndex];
+                    var segment = segments[segmentIndex];
                     if (parameterName != null && segment.Length > 0)
                     {
-                        slots[captures[i].slotIndex] = new KeyValuePair<string, object>(
+                        slots[slotIndex] = new KeyValuePair<string, object>(
                             parameterName,
                             path.Substring(segment.Start, segment.Length));
                     }
@@ -249,7 +250,7 @@ namespace Microsoft.AspNetCore.Routing.Matching
             ReadOnlySpan<PathSegment> segments)
         {
             // Read segmentIndex to local both to skip double read from stack value
-            // and to use the same in-bounds validated varaible to access the array.
+            // and to use the same in-bounds validated variable to access the array.
             var segmentIndex = catchAll.segmentIndex;
             if ((uint)segmentIndex < (uint)segments.Length)
             {
@@ -271,7 +272,7 @@ namespace Microsoft.AspNetCore.Routing.Matching
             {
                 (var complexSegment, var segmentIndex) = complexSegments[i];
                 var segment = segments[segmentIndex];
-                var text = path.Substring(segment.Start, segment.Length);
+                var text = path.AsSpan(segment.Start, segment.Length);
                 if (!RoutePatternMatcher.MatchComplexSegment(complexSegment, text, values))
                 {
                     Logger.CandidateRejectedByComplexSegment(_logger, path, endpoint, complexSegment);
diff --git a/src/Http/Routing/src/Patterns/RoutePatternMatcher.cs b/src/Http/Routing/src/Patterns/RoutePatternMatcher.cs
index 7f90c882af..bb35818703 100644
--- a/src/Http/Routing/src/Patterns/RoutePatternMatcher.cs
+++ b/src/Http/Routing/src/Patterns/RoutePatternMatcher.cs
@@ -160,7 +160,7 @@ namespace Microsoft.AspNetCore.Routing
                 }
                 if (!pathSegment.IsSimple)
                 {
-                    if (!MatchComplexSegment(pathSegment, requestSegment.ToString(), values))
+                    if (!MatchComplexSegment(pathSegment, requestSegment.AsSpan(), values))
                     {
                         return false;
                     }
@@ -292,7 +292,7 @@ namespace Microsoft.AspNetCore.Routing
 
         internal static bool MatchComplexSegment(
             RoutePatternPathSegment routeSegment,
-            string requestSegment,
+            ReadOnlySpan<char> requestSegment,
             RouteValueDictionary values)
         {
             var indexOfLastSegment = routeSegment.Parts.Count - 1;
@@ -336,7 +336,7 @@ namespace Microsoft.AspNetCore.Routing
 
         private static bool MatchComplexSegmentCore(
             RoutePatternPathSegment routeSegment,
-            string requestSegment,
+            ReadOnlySpan<char> requestSegment,
             RouteValueDictionary values,
             int indexOfLastSegmentUsed)
         {
@@ -366,14 +366,14 @@ namespace Microsoft.AspNetCore.Routing
                     Debug.Assert(part.IsLiteral || part.IsSeparator);
                     lastLiteral = part;
 
-                    var startIndex = lastIndex - 1;
+                    var startIndex = lastIndex;
                     // If we have a pending parameter subsegment, we must leave at least one character for that
                     if (parameterNeedsValue != null)
                     {
                         startIndex--;
                     }
 
-                    if (startIndex < 0)
+                    if (startIndex == 0)
                     {
                         return false;
                     }
@@ -382,17 +382,15 @@ namespace Microsoft.AspNetCore.Routing
                     if (part.IsLiteral)
                     {
                         var literal = (RoutePatternLiteralPart)part;
-                        indexOfLiteral = requestSegment.LastIndexOf(
+                        indexOfLiteral = requestSegment.Slice(0, startIndex).LastIndexOf(
                         literal.Content,
-                        startIndex,
                         StringComparison.OrdinalIgnoreCase);
                     }
                     else
                     {
                         var literal = (RoutePatternSeparatorPart)part;
-                        indexOfLiteral = requestSegment.LastIndexOf(
+                        indexOfLiteral = requestSegment.Slice(0, startIndex).LastIndexOf(
                         literal.Content,
-                        startIndex,
                         StringComparison.OrdinalIgnoreCase);
                     }
 
@@ -465,9 +463,9 @@ namespace Microsoft.AspNetCore.Routing
                         }
                     }
 
-                    var parameterValueString = requestSegment.Substring(parameterStartIndex, parameterTextLength);
+                    var parameterValueSpan = requestSegment.Slice(parameterStartIndex, parameterTextLength);
 
-                    if (string.IsNullOrEmpty(parameterValueString))
+                    if (parameterValueSpan.Length == 0)
                     {
                         // If we're here that means we have a segment that contains multiple sub-segments.
                         // For these segments all parameters must have non-empty values. If the parameter
@@ -478,7 +476,7 @@ namespace Microsoft.AspNetCore.Routing
                     else
                     {
                         // If there's a value in the segment for this parameter, use the subsegment value
-                        outValues.Add(parameterNeedsValue.Name, parameterValueString);
+                        outValues.Add(parameterNeedsValue.Name, new string(parameterValueSpan));
                     }
 
                     parameterNeedsValue = null;