diff --git a/Src/ConfigurationReader.cs b/Src/ConfigurationReader.cs
index 369b207..b5b2647 100644
--- a/Src/ConfigurationReader.cs
+++ b/Src/ConfigurationReader.cs
@@ -4,6 +4,7 @@
 using System;
 using System.IO;
 using System.Text;
+using System.Collections.Generic;
 
 namespace SharpConfig
 {
@@ -25,6 +26,7 @@ private static void Parse(StringReader reader, Configuration config)
     {
       var currentSection = new Section(Section.DefaultSectionName);
       var preCommentBuilder = new StringBuilder();
+      HashSet<char> validCommentChars = new HashSet<char>(Configuration.ValidCommentChars); // Initialize once for each reader to optimize performance
 
       int lineNumber = 0;
 
@@ -44,7 +46,7 @@ private static void Parse(StringReader reader, Configuration config)
           continue;
         }
 
-        var comment = ParseComment(line, out int commentIndex);
+        var comment = ParseComment(line, validCommentChars, out int commentIndex);
 
         if (commentIndex == 0)
         {
@@ -108,7 +110,7 @@ private static void Parse(StringReader reader, Configuration config)
       }
     }
 
-    private static string ParseComment(string line, out int commentCharIndex)
+    private static string ParseComment(string line, HashSet<char> validCommentChars, out int commentCharIndex)
     {
       // A comment starts with a valid comment character that:
       // 1. is not within a quote (eg. "this is # not a comment"), and
@@ -122,11 +124,13 @@ private static string ParseComment(string line, out int commentCharIndex)
 
       int index = 0;
       int quoteCount = 0;
-      while (line.Length > index) // traverse line from left to right
+      int length = line.Length;
+      while (index < length) // traverse line from left to right
       {
-        bool isValidCommentChar = Array.IndexOf(Configuration.ValidCommentChars, line[index]) > -1;
-        bool isQuotationMark = line[index] == '\"';
-        bool isCharWithinQuotes = quoteCount % 2 == 1;
+        char currentChar = line[index];
+        bool isValidCommentChar = validCommentChars.Contains(currentChar);
+        bool isQuotationMark = currentChar == '\"';
+        bool isCharWithinQuotes = (quoteCount & 1) == 1; // bitwise AND is slightly faster
         bool isCharEscaped = index > 0 && line[index - 1] == '\\';
 
         if (isValidCommentChar && !isCharWithinQuotes && !isCharEscaped)