diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61f24ea..03005d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,11 +8,21 @@ All notable changes to **ValueStringBuilder** will be documented in this file. T
 
 This is the `v2` release of the **ValueStringBuilder**. There aren't any noticeable changes. Only old framework versions were removed to make further development easier.
 
+### Added
+
+- Added `Append(Rune)` overload
+- Added `AppendJoin(Rune, IEnumerable<string?>)` overload
+- Added `AppendJoin<T>(Rune, IEnumerable<T>)` overload
+
 ### Removed
+
 - Support for `net6.0` and `net7.0` was removed.
 
 ### Changed
+
 - Added `OverloadResolutionPriority` for `Span` overload for the ctor to keep the current behavior. Reported by [@nsentinel])(https://github.com/nsentinel) in [#210](https://github.com/linkdotnet/StringBuilder/issues/210).
+- Optimised `AppendLine(scoped ReadOnlySpan<char>)` by avoiding allocating a new string
+- Removed erroneous null check in `AppendJoin<T>(ReadOnlySpan<char>, IEnumerable<T>)`
 
 ## [1.22.0] - 2024-12-18
 
diff --git a/src/LinkDotNet.StringBuilder/ValueStringBuilder.Append.cs b/src/LinkDotNet.StringBuilder/ValueStringBuilder.Append.cs
index 0bbc6bb..c3259e0 100644
--- a/src/LinkDotNet.StringBuilder/ValueStringBuilder.Append.cs
+++ b/src/LinkDotNet.StringBuilder/ValueStringBuilder.Append.cs
@@ -1,5 +1,6 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Text;
 
 namespace LinkDotNet.StringBuilder;
 
@@ -117,6 +118,20 @@ public void Append(char value)
         bufferPosition++;
     }
 
+    /// <summary>
+    /// Appends a single rune to the string builder.
+    /// </summary>
+    /// <param name="value">Rune to add.</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void Append(Rune value)
+    {
+        Span<char> valueChars = stackalloc char[2];
+        int valueCharsWritten = value.EncodeToUtf16(valueChars);
+        ReadOnlySpan<char> valueCharsReadOnly = valueChars[..valueCharsWritten];
+
+        Append(valueCharsReadOnly);
+    }
+
     /// <summary>
     /// Adds the default new line separator.
     /// </summary>
@@ -129,11 +144,12 @@ public void AppendLine()
     /// <summary>
     /// Does the same as <see cref="Append(char)"/> but adds a newline at the end.
     /// </summary>
-    /// <param name="str">String, which will be added to this builder.</param>
+    /// <param name="str">String to be added to this builder.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void AppendLine(scoped ReadOnlySpan<char> str)
     {
-        Append(string.Concat(str, Environment.NewLine));
+        Append(str);
+        Append(Environment.NewLine);
     }
 
     /// <summary>
diff --git a/src/LinkDotNet.StringBuilder/ValueStringBuilder.AppendJoin.cs b/src/LinkDotNet.StringBuilder/ValueStringBuilder.AppendJoin.cs
index a6241c5..b7bdb76 100644
--- a/src/LinkDotNet.StringBuilder/ValueStringBuilder.AppendJoin.cs
+++ b/src/LinkDotNet.StringBuilder/ValueStringBuilder.AppendJoin.cs
@@ -1,4 +1,5 @@
 using System.Runtime.CompilerServices;
+using System.Text;
 
 namespace LinkDotNet.StringBuilder;
 
@@ -8,7 +9,7 @@ public ref partial struct ValueStringBuilder
     /// Concatenates and appends all values with the given separator between each entry at the end of the string.
     /// </summary>
     /// <param name="separator">String used as separator between the entries.</param>
-    /// <param name="values">Array of strings, which will be concatenated.</param>
+    /// <param name="values">Enumerable of strings to be concatenated.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void AppendJoin(ReadOnlySpan<char> separator, IEnumerable<string?> values)
         => AppendJoinInternalString(separator, values);
@@ -17,17 +18,26 @@ public void AppendJoin(ReadOnlySpan<char> separator, IEnumerable<string?> values
     /// Concatenates and appends all values with the given separator between each entry at the end of the string.
     /// </summary>
     /// <param name="separator">Character used as separator between the entries.</param>
-    /// <param name="values">Array of strings, which will be concatenated.</param>
+    /// <param name="values">Enumerable of strings to be concatenated.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void AppendJoin(char separator, IEnumerable<string?> values)
         => AppendJoinInternalChar(separator, values);
 
+    /// <summary>
+    /// Concatenates and appends all values with the given separator between each entry at the end of the string.
+    /// </summary>
+    /// <param name="separator">Rune used as separator between the entries.</param>
+    /// <param name="values">Enumerable of strings to be concatenated.</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void AppendJoin(Rune separator, IEnumerable<string?> values)
+        => AppendJoinInternalRune(separator, values);
+
     /// <summary>
     /// Concatenates and appends all values with the given separator between each entry at the end of the string.
     /// </summary>
     /// <param name="separator">String used as separator between the entries.</param>
-    /// <param name="values">Array of strings, which will be concatenated.</param>
-    /// <typeparam name="T">Type of the given array.</typeparam>
+    /// <param name="values">Enumerable to be concatenated.</param>
+    /// <typeparam name="T">Type of the given enumerable.</typeparam>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void AppendJoin<T>(ReadOnlySpan<char> separator, IEnumerable<T> values)
         => AppendJoinInternalString(separator, values);
@@ -36,12 +46,22 @@ public void AppendJoin<T>(ReadOnlySpan<char> separator, IEnumerable<T> values)
     /// Concatenates and appends all values with the given separator between each entry at the end of the string.
     /// </summary>
     /// <param name="separator">Character used as separator between the entries.</param>
-    /// <param name="values">Array of strings, which will be concatenated.</param>
-    /// <typeparam name="T">Type of the given array.</typeparam>
+    /// <param name="values">Enumerable to be concatenated.</param>
+    /// <typeparam name="T">Type of the given enumerable.</typeparam>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void AppendJoin<T>(char separator, IEnumerable<T> values)
         => AppendJoinInternalChar(separator, values);
 
+    /// <summary>
+    /// Concatenates and appends all values with the given separator between each entry at the end of the string.
+    /// </summary>
+    /// <param name="separator">Rune used as separator between the entries.</param>
+    /// <param name="values">Enumerable to be concatenated.</param>
+    /// <typeparam name="T">Type of the given enumerable.</typeparam>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void AppendJoin<T>(Rune separator, IEnumerable<T> values)
+        => AppendJoinInternalRune(separator, values);
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private void AppendJoinInternalString<T>(ReadOnlySpan<char> separator, IEnumerable<T> values)
     {
@@ -55,10 +75,7 @@ private void AppendJoinInternalString<T>(ReadOnlySpan<char> separator, IEnumerab
         }
 
         var current = enumerator.Current;
-        if (current is not null)
-        {
-            AppendInternal(current);
-        }
+        AppendInternal(current);
 
         while (enumerator.MoveNext())
         {
@@ -91,6 +108,29 @@ private void AppendJoinInternalChar<T>(char separator, IEnumerable<T> values)
         }
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private void AppendJoinInternalRune<T>(Rune separator, IEnumerable<T> values)
+    {
+        ArgumentNullException.ThrowIfNull(values);
+
+        using var enumerator = values.GetEnumerator();
+
+        if (!enumerator.MoveNext())
+        {
+            return;
+        }
+
+        var current = enumerator.Current;
+        AppendInternal(current);
+
+        while (enumerator.MoveNext())
+        {
+            Append(separator);
+            current = enumerator.Current;
+            AppendInternal(current);
+        }
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private void AppendInternal<T>(T value)
     {