diff --git a/src/libraries/System.Private.CoreLib/src/System/Char.cs b/src/libraries/System.Private.CoreLib/src/System/Char.cs
index 7df1b14afc0332..42980bb3f48b53 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Char.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Char.cs
@@ -274,7 +274,7 @@ internal static bool TryParse(ReadOnlySpan<char> s, out char result)
         /// This determines whether the character is in the range 'A' through 'Z', inclusive,
         /// 'a' through 'z', inclusive, or '0' through '9', inclusive.
         /// </remarks>
-        public static bool IsAsciiLetterOrDigit(char c) => IsAsciiLetter(c) | IsBetween(c, '0', '9');
+        public static bool IsAsciiLetterOrDigit(char c) => IsAsciiLetter(c) | IsBetween(c, '0', '9');  // Using | here is an optimization (avoids branching).
 
         /// <summary>Indicates whether a character is categorized as an ASCII hexadecimal digit.</summary>
         /// <param name="c">The character to evaluate.</param>