diff --git a/Src/Configuration.cs b/Src/Configuration.cs
index 4c0960f..27caf4f 100644
--- a/Src/Configuration.cs
+++ b/Src/Configuration.cs
@@ -35,7 +35,7 @@ static Configuration()
       // but without modifying the real invariant culture instance.
       s_cultureInfo = (CultureInfo)CultureInfo.InvariantCulture.Clone();
 
-      ValidCommentChars = new[] { '#', ';' };
+      ValidCommentChars = new HashSet<char> { '#', ';' };
       s_preferredCommentChar = '#';
       s_arrayElementSeparator = ',';
 
@@ -585,7 +585,7 @@ public static CultureInfo CultureInfo
     /// Gets the array that contains all valid comment delimiting characters.
     /// The current value is { '#', ';' }.
     /// </summary>
-    public static char[] ValidCommentChars { get; private set; }
+    public static HashSet<char> ValidCommentChars { get; private set; }
 
     /// <summary>
     /// Gets or sets the preferred comment char when saving configurations.
@@ -597,7 +597,7 @@ public static char PreferredCommentChar
     {
       get => s_preferredCommentChar;
       set {
-        if (!Array.Exists(ValidCommentChars, c => c == value))
+        if (!ValidCommentChars.Contains(value))
         {
           throw new ArgumentException("The specified char '" + value + "' is not allowed as a comment char.");
         }
diff --git a/Src/ConfigurationReader.cs b/Src/ConfigurationReader.cs
index 0d34c7b..d6c430b 100644
--- a/Src/ConfigurationReader.cs
+++ b/Src/ConfigurationReader.cs
@@ -124,11 +124,13 @@ private static string ParseComment(string line, out int commentCharIndex)
       var index = 0;
       var quoteCount = 0;
 
-      while (line.Length > index) // traverse line from left to right
+      var length = line.Length;
+      while (index < length) // traverse line from left to right
       {
-        var isValidCommentChar = Array.IndexOf(Configuration.ValidCommentChars, line[index]) > -1;
-        var isQuotationMark = line[index] == '\"';
-        var isCharWithinQuotes = quoteCount % 2 == 1;
+        var currentChar = line[index];
+        var isValidCommentChar = Configuration.ValidCommentChars.Contains(currentChar);
+        var isQuotationMark = currentChar == '\"';
+        var isCharWithinQuotes = (quoteCount & 1) == 1; // bitwise AND is slightly faster
         var isCharEscaped = index > 0 && line[index - 1] == '\\';
 
         if (isValidCommentChar && !isCharWithinQuotes && !isCharEscaped)
diff --git a/Src/Setting.cs b/Src/Setting.cs
index fdfa459..307b857 100644
--- a/Src/Setting.cs
+++ b/Src/Setting.cs
@@ -2,6 +2,7 @@
 // https://sharpconfig.org
 
 using System;
+using System.Linq;
 using System.Text;
 
 namespace SharpConfig
@@ -612,8 +613,10 @@ private static string GetValueForOutput(string rawValue)
         return rawValue;
       }
 
+      bool isAnyCommentCharInRawValue() => rawValue.Any(c => Configuration.ValidCommentChars.Contains(c));
+
       if (rawValue.IndexOf(" ", StringComparison.Ordinal) >= 0 ||
-          (rawValue.IndexOfAny(Configuration.ValidCommentChars) >= 0 && !Configuration.IgnoreInlineComments))
+          (isAnyCommentCharInRawValue() && !Configuration.IgnoreInlineComments))
       {
         rawValue = "\"" + rawValue + "\"";
       }