diff --git a/Sources/Element.swift b/Sources/Element.swift
index 8b4c67b..63e3cd1 100644
--- a/Sources/Element.swift
+++ b/Sources/Element.swift
@@ -16,9 +16,6 @@ open class Element: Node {
     private static let idString = "id".utf8Array
     private static let rootString = "#root".utf8Array
 
-    //private static let classSplit : Pattern = Pattern("\\s+")
-	private static let classSplit = "\\s+"
-
     /**
      * Create a new, standalone Element. (Standalone in that is has no parent.)
      *
@@ -1112,6 +1109,15 @@ open class Element: Node {
     public func className() throws -> String {
         return try String(decoding: attr(Element.classString).trim(), as: UTF8.self)
     }
+    
+    /**
+     * Gets the literal value of this element's "class" attribute, which may include multiple class names, space
+     * separated. (E.g. on <code>&lt;div class="header gray"&gt;</code> returns, "<code>header gray</code>")
+     * @return The literal class attribute, or <b>empty string</b> if no class attribute set.
+     */
+    public func classNameUTF8() throws -> [UInt8] {
+        return try attr(Element.classString).trim()
+    }
 
     /**
      * Get all of the element's class names. E.g. on element {@code <div class="header gray">},
@@ -1119,13 +1125,36 @@ open class Element: Node {
      * the backing {@code class} attribute; use the {@link #classNames(java.util.Set)} method to persist them.
      * @return set of classnames, empty if no class attribute
      */
-	public func classNames() throws -> OrderedSet<String> {
-        let fitted = try className().replaceAll(of: Element.classSplit, with: " ", options: .caseInsensitive)
-		let names: [String] = fitted.components(separatedBy: " ")
-		let classNames: OrderedSet<String> = OrderedSet(sequence: names)
-		classNames.remove("") // if classNames() was empty, would include an empty class
-		return classNames
-	}
+    public func classNames() throws -> OrderedSet<String> {
+        let utf8ClassName = try classNameUTF8()
+        var classNames = OrderedSet<String>()
+        var currentStartIndex: Int? = nil
+        
+        for (i, byte) in utf8ClassName.enumerated() {
+            if byte.isWhitespace {
+                if let start = currentStartIndex {
+                    let classBytes = utf8ClassName[start..<i]
+                    if !classBytes.isEmpty {
+                        classNames.append(String(decoding: classBytes, as: UTF8.self))
+                    }
+                    currentStartIndex = nil
+                }
+            } else {
+                if currentStartIndex == nil {
+                    currentStartIndex = i
+                }
+            }
+        }
+        
+        if let start = currentStartIndex {
+            let classBytes = utf8ClassName[start..<utf8ClassName.count]
+            if !classBytes.isEmpty {
+                classNames.append(String(decoding: classBytes, as: UTF8.self))
+            }
+        }
+        
+        return classNames
+    }
 
     /**
      Set the element's {@code class} attribute to the supplied class names.
@@ -1302,13 +1331,13 @@ open class Element: Node {
      * @return String of HTML.
      * @see #outerHtml()
      */
-    public func html()throws->String {
+    public func html() throws -> String {
         let accum: StringBuilder = StringBuilder()
         try html2(accum)
         return getOutputSettings().prettyPrint() ? accum.toString().trim() : accum.toString()
     }
 
-    private func html2(_ accum: StringBuilder)throws {
+    private func html2(_ accum: StringBuilder) throws {
         for node in childNodes {
             try node.outerHtml(accum)
         }
diff --git a/Sources/Node.swift b/Sources/Node.swift
index 56e2701..bc5a785 100644
--- a/Sources/Node.swift
+++ b/Sources/Node.swift
@@ -533,12 +533,14 @@ open class Node: Equatable, Hashable {
      * Replace this node in the DOM with the supplied node.
      * @param in the node that will will replace the existing node.
      */
+    @inlinable
     public func replaceWith(_ input: Node) throws {
         try Validate.notNull(obj: input)
         try Validate.notNull(obj: parentNode)
         try parentNode?.replaceChild(self, input)
     }
 
+    @inlinable
     public func setParentNode(_ parentNode: Node) throws {
         if (self.parentNode != nil) {
         try self.parentNode?.removeChild(self)
@@ -546,6 +548,7 @@ open class Node: Equatable, Hashable {
         self.parentNode = parentNode
     }
 
+    @inlinable
     public func replaceChild(_ out: Node, _ input: Node) throws {
         try Validate.isTrue(val: out.parentNode === self)
         try Validate.notNull(obj: input)
@@ -554,17 +557,16 @@ open class Node: Equatable, Hashable {
         }
 
         let index: Int = out.siblingIndex
-        let replacing = childNodes[index]
         childNodes[index] = input
         input.parentNode = self
         input.setSiblingIndex(index)
         out.parentNode = nil
     }
 
+    @inlinable
     public func removeChild(_ out: Node) throws {
         try Validate.isTrue(val: out.parentNode === self)
         let index: Int = out.siblingIndex
-        let removing = childNodes[index]
         childNodes.remove(at: index)
         reindexChildren(index)
         out.parentNode = nil
@@ -586,10 +588,12 @@ open class Node: Equatable, Hashable {
         }
     }
 
+    @inlinable
     public func addChildren(_ index: Int, _ children: Node...) throws {
         try addChildren(index, children)
     }
 
+    @inlinable
     public func addChildren(_ index: Int, _ children: [Node]) throws {
         for i in (0..<children.count).reversed() {
             let input: Node = children[i]
@@ -599,12 +603,14 @@ open class Node: Equatable, Hashable {
         }
     }
 
+    @inlinable
     public func reparentChild(_ child: Node)throws {
         try child.parentNode?.removeChild(child)
         try child.setParentNode(self)
     }
     
-    private func reindexChildren(_ start: Int) {
+    @usableFromInline
+    internal func reindexChildren(_ start: Int) {
         for (index, node) in childNodes[start...].enumerated() {
             node.setSiblingIndex(start + index)
         }
@@ -831,7 +837,6 @@ open class Node: Equatable, Hashable {
         }
 
         open func head(_ node: Node, _ depth: Int)throws {
-
             try node.outerHtmlHead(accum, depth, out)
         }
 
diff --git a/Sources/StringBuilder.swift b/Sources/StringBuilder.swift
index 2cec837..fb9f7a3 100755
--- a/Sources/StringBuilder.swift
+++ b/Sources/StringBuilder.swift
@@ -10,11 +10,11 @@ open class StringBuilder {
      
      :param: string Initial value; defaults to empty string
      */
-    public init(string: String = "") {
-        if !string.isEmpty {
+    public init(string: String? = nil) {
+        if let string, !string.isEmpty {
             buffer.append(contentsOf: string.utf8)
         }
-        buffer.reserveCapacity(string.utf8.count ?? 128)
+        buffer.reserveCapacity(1024)
     }
     
     public init(_ size: Int) {