diff --git a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ExtendedStringLiteral.java b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ExtendedStringLiteral.java
index 619ed21c7aa..b1e46ac4e78 100644
--- a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ExtendedStringLiteral.java
+++ b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ExtendedStringLiteral.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2009 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -18,8 +18,8 @@
 
 public class ExtendedStringLiteral extends StringLiteral {
 
-	public ExtendedStringLiteral(char[] token, int start, int end, int lineNumber) {
-		super(token, start, end, lineNumber);
+	protected ExtendedStringLiteral(StringLiteral optionalHead, Object sourcesTail, int start, int end, int lineNumber) {
+		super(optionalHead, sourcesTail, start,  end,  lineNumber);
 	}
 
 	@Override
diff --git a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteral.java b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteral.java
index 26ca56a79c7..08fa3c8f5ec 100644
--- a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteral.java
+++ b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteral.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2014 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -13,8 +13,6 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.compiler.ast;
 
-import java.util.Arrays;
-
 import org.eclipse.jdt.internal.compiler.ASTVisitor;
 import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
 import org.eclipse.jdt.internal.compiler.impl.StringConstant;
@@ -24,42 +22,50 @@
 
 public class StringLiteral extends Literal {
 
-	private char[] source;
+	/** may be null, prefixes tail **/
+	protected StringLiteral optionalHead;
+	/** StringLiteral or char[] tail **/
+	protected Object tail;
+	/** zero based **/
 	private final int lineNumber;
 
-	public StringLiteral(char[] token, int start, int end, int lineNumber) {
+	public StringLiteral(char[] token, int start, int end, int lineNumber1based) {
+		this(null, token, start, end, lineNumber1based - 1);
+	}
+
+	protected StringLiteral(StringLiteral optionalHead, Object tail, int start, int end, int lineNumber) {
 		super(start, end);
-		this.source = token;
-		this.lineNumber = lineNumber - 1; // line number is 1 based
+		this.optionalHead = optionalHead;
+		this.tail = tail;
+		this.lineNumber = lineNumber;
 	}
 
 	public StringLiteral(int s, int e) {
-		this(null, s, e, 1);
+		this(null, null, s, e, 0);
 	}
 
 	@Override
 	public void computeConstant() {
-		this.constant = StringConstant.fromValue(String.valueOf(this.source));
+		this.constant = StringConstant.fromValue(String.valueOf(this.source()));
 	}
 
+	/**
+	 * creates a copy of dedicated Type for optimizeStringLiterals with the given CharLiteral appended
+	 */
 	public ExtendedStringLiteral extendWith(CharLiteral lit) {
-		return new ExtendedStringLiteral(append(this.source(), new char[] { lit.value }),
-				this.sourceStart, lit.sourceEnd, this.getLineNumber() + 1);
+		char[] charTail = new char[] { lit.value };
+		return new ExtendedStringLiteral(this, charTail, this.sourceStart, lit.sourceEnd, this.getLineNumber());
 	}
 
+	/**
+	 * creates a copy of dedicated Type for optimizeStringLiterals with the given StringLiteral appended
+	 */
 	public ExtendedStringLiteral extendWith(StringLiteral lit) {
-		return new ExtendedStringLiteral(append(this.source(), lit.source()), this.sourceStart,
-				lit.sourceEnd, this.getLineNumber() + 1);
-	}
-	protected static char[] append(char[] source, char[] source2) {
-		char[] result = Arrays.copyOfRange(source, 0, source.length + source2.length);
-		System.arraycopy(source2, 0, result, source.length, source2.length);
-		return result;
+		return new ExtendedStringLiteral(this, lit, this.sourceStart, lit.sourceEnd, this.getLineNumber());
 	}
 
-
 	/**
-	 * Add the lit source to mine, just as if it was mine
+	 * creates a copy of dedicated Type for unoptimizeStringLiterals with the given StringLiteral appended
 	 */
 	public StringLiteralConcatenation extendsWith(StringLiteral lit) {
 		return new StringLiteralConcatenation(this, lit);
@@ -94,7 +100,35 @@ public StringBuilder printExpression(int indent, StringBuilder output) {
 
 	@Override
 	public char[] source() {
-		return Arrays.copyOf(this.source, this.source.length);
+		if (this.optionalHead == null && this.tail instanceof char[] ch) {
+			// fast path without copy
+			return ch;
+		}
+		// flatten linked list to char[]
+		int size = append(null, 0, this);
+		char[] result = new char[size];
+		append(result, 0, this);
+		flatten(result);
+		return result;
+	}
+
+	protected void flatten(char[] result) {
+		setSource(result); // keep flat version
+	}
+
+	private static int append(char[] result, int length, StringLiteral o) {
+		do {
+			if (o.tail instanceof char[] c) {
+				if (result != null) {
+					System.arraycopy(c, 0, result, result.length - c.length - length, c.length);
+				}
+				length += c.length;
+			} else {
+				length = append(result, length, ((StringLiteral) o.tail));
+			}
+			o = o.optionalHead;
+		} while (o != null);
+		return length;
 	}
 
 	@Override
@@ -104,7 +138,8 @@ public void traverse(ASTVisitor visitor, BlockScope scope) {
 	}
 
 	public void setSource(char[] source) {
-		this.source = source;
+		this.tail = source;
+		this.optionalHead = null;
 	}
 
 	public int getLineNumber() {
diff --git a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteralConcatenation.java b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteralConcatenation.java
index c0fc638a2ec..0644b89f54e 100644
--- a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteralConcatenation.java
+++ b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/StringLiteralConcatenation.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2009 IBM Corporation and others.
+ * Copyright (c) 2000, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -13,8 +13,6 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.compiler.ast;
 
-import java.util.Arrays;
-
 import org.eclipse.jdt.internal.compiler.ASTVisitor;
 import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
 
@@ -22,25 +20,12 @@
  * Flatten string literal
  */
 public class StringLiteralConcatenation extends StringLiteral {
-	private static final int INITIAL_SIZE = 5;
-	private final StringLiteral[] literals;
-	private final int counter;
 
 	/**
 	 * Build a two-strings literal
 	 */
-	public StringLiteralConcatenation(StringLiteral str1, StringLiteral str2) {
-		super(StringLiteral.append(str1.source(), str2.source()), str1.sourceStart, str2.sourceEnd,
-				str1.getLineNumber() + 1);
-		if (str1 instanceof StringLiteralConcatenation s1) {
-			this.literals = Arrays.copyOf(s1.literals, s1.literals.length + 1);
-			this.counter = s1.counter + 1;
-		} else {
-			this.literals = new StringLiteral[INITIAL_SIZE];
-			this.literals[0] = str1;
-			this.counter = 2;
-		}
-		this.literals[this.counter - 1] = str2;
+	public StringLiteralConcatenation(StringLiteral str1, StringLiteral lit) {
+		super(str1, lit, str1.sourceStart, lit.sourceEnd, str1.getLineNumber());
 	}
 
 	@Override
@@ -64,6 +49,38 @@ public void traverse(ASTVisitor visitor, BlockScope scope) {
 	}
 
 	public StringLiteral[] getLiterals() {
-		return Arrays.copyOf(this.literals, this.counter);
+		int size = append(null, 0, this);
+		StringLiteral[] result = new StringLiteral[size];
+		append(result, 0, this);
+		return result;
+	}
+
+	private static int append(StringLiteral[] result, int length, StringLiteral o) {
+		do {
+			if (o.tail instanceof StringLiteral l) {
+				if (result != null) {
+					result[result.length - 1 - length] = l;
+				}
+				length += 1;
+			} else {
+				if (result != null) {
+					result[result.length - 1 - length] = o;
+				}
+				length += 1;
+			}
+			o = o.optionalHead;
+		} while (o != null);
+		return length;
+	}
+
+	@Override
+	protected void flatten(char[] result) {
+		// don't store flattened representation: getLiterals() still needs the linked list
+	}
+
+	@Override
+	public void setSource(char[] source) {
+		throw new UnsupportedOperationException();
 	}
-}
+
+}
\ No newline at end of file