diff --git a/JSONArray.java b/JSONArray.java
index 8ac58441b..c876f42a9 100644
--- a/JSONArray.java
+++ b/JSONArray.java
@@ -25,8 +25,6 @@ of this software and associated documentation files (the "Software"), to deal
  */
 
 import java.io.IOException;
-import java.io.StringWriter;
-import java.io.Writer;
 import java.lang.reflect.Array;
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -78,7 +76,7 @@ of this software and associated documentation files (the "Software"), to deal
  * </ul>
  *
  * @author JSON.org
- * @version 2016-07-19
+ * @version 2016-08-04
  */
 public class JSONArray implements Iterable<Object> {
 
@@ -447,7 +445,7 @@ public String join(String separator) throws JSONException {
             if (i > 0) {
                 sb.append(separator);
             }
-            sb.append(JSONObject.valueToString(this.myArrayList.get(i)));
+            JSONObject.writeValue(sb, this.myArrayList.get(i));
         }
         return sb.toString();
     }
@@ -1017,7 +1015,7 @@ public JSONArray put(int index, Object value) throws JSONException {
     }
     
     /**
-     * Creates a JSONPointer using an initialization string and tries to
+     * Creates a JSONPointer using an initialization string and tries to 
      * match it to an item within this JSONArray. For example, given a
      * JSONArray initialized with this document:
      * <pre>
@@ -1159,10 +1157,8 @@ public String toString() {
      * @throws JSONException
      */
     public String toString(int indentFactor) throws JSONException {
-        StringWriter sw = new StringWriter();
-        synchronized (sw.getBuffer()) {
-            return this.write(sw, indentFactor, 0).toString();
-        }
+        StringBuilder sw = new StringBuilder();
+        return this.write(sw, indentFactor, 0).toString();
     }
 
     /**
@@ -1174,7 +1170,7 @@ public String toString(int indentFactor) throws JSONException {
      * @return The writer.
      * @throws JSONException
      */
-    public Writer write(Writer writer) throws JSONException {
+    public <T extends Appendable> T write(T writer) throws JSONException {
         return this.write(writer, 0, 0);
     }
 
@@ -1193,12 +1189,12 @@ public Writer write(Writer writer) throws JSONException {
      * @return The writer.
      * @throws JSONException
      */
-    public Writer write(Writer writer, int indentFactor, int indent)
+    public <T extends Appendable> T write(T writer, int indentFactor, int indent)
             throws JSONException {
         try {
             boolean commanate = false;
             int length = this.length();
-            writer.write('[');
+            writer.append('[');
 
             if (length == 1) {
                 JSONObject.writeValue(writer, this.myArrayList.get(0),
@@ -1208,10 +1204,10 @@ public Writer write(Writer writer, int indentFactor, int indent)
 
                 for (int i = 0; i < length; i += 1) {
                     if (commanate) {
-                        writer.write(',');
+                        writer.append(',');
                     }
                     if (indentFactor > 0) {
-                        writer.write('\n');
+                        writer.append('\n');
                     }
                     JSONObject.indent(writer, newindent);
                     JSONObject.writeValue(writer, this.myArrayList.get(i),
@@ -1219,11 +1215,11 @@ public Writer write(Writer writer, int indentFactor, int indent)
                     commanate = true;
                 }
                 if (indentFactor > 0) {
-                    writer.write('\n');
+                    writer.append('\n');
                 }
                 JSONObject.indent(writer, indent);
             }
-            writer.write(']');
+            writer.append(']');
             return writer;
         } catch (IOException e) {
             throw new JSONException(e);
diff --git a/JSONObject.java b/JSONObject.java
index 8fb0a2569..20cdaa270 100644
--- a/JSONObject.java
+++ b/JSONObject.java
@@ -25,8 +25,6 @@ of this software and associated documentation files (the "Software"), to deal
  */
 
 import java.io.IOException;
-import java.io.StringWriter;
-import java.io.Writer;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -93,7 +91,7 @@ of this software and associated documentation files (the "Software"), to deal
  * </ul>
  *
  * @author JSON.org
- * @version 2016-07-19
+ * @version 2016-08-04
  */
 public class JSONObject {
     /**
@@ -1442,21 +1440,19 @@ public Object optQuery(String jsonPointer) {
      *            A String
      * @return A String correctly formatted for insertion in a JSON text.
      */
-    public static String quote(String string) {
-        StringWriter sw = new StringWriter();
-        synchronized (sw.getBuffer()) {
-            try {
-                return quote(string, sw).toString();
-            } catch (IOException ignored) {
-                // will never happen - we are writing to a string writer
-                return "";
-            }
+    public static String quote(CharSequence string) {
+        StringBuilder sb = new StringBuilder();
+        try {
+            return quote(string, sb).toString();
+        } catch (IOException ignored) {
+            // will never happen - we are writing to a string builder
+            return "";
         }
     }
 
-    public static Writer quote(String string, Writer w) throws IOException {
+    public static <T extends Appendable> T quote(CharSequence string, T w) throws IOException {
         if (string == null || string.length() == 0) {
-            w.write("\"\"");
+            w.append("\"\"");
             return w;
         }
 
@@ -1465,51 +1461,84 @@ public static Writer quote(String string, Writer w) throws IOException {
         String hhhh;
         int i;
         int len = string.length();
+        int prev = 0;
 
-        w.write('"');
+        w.append('"');
         for (i = 0; i < len; i += 1) {
             b = c;
             c = string.charAt(i);
             switch (c) {
             case '\\':
             case '"':
-                w.write('\\');
-                w.write(c);
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append('\\');
+                prev = i;
                 break;
             case '/':
                 if (b == '<') {
-                    w.write('\\');
+                    if(prev < i) {
+                        w.append(string, prev, i);
+                    }
+                    w.append('\\');
+                    prev = i;
                 }
-                w.write(c);
                 break;
             case '\b':
-                w.write("\\b");
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append("\\b");
+                prev = i + 1;
                 break;
             case '\t':
-                w.write("\\t");
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append("\\t");
+                prev = i + 1;
                 break;
             case '\n':
-                w.write("\\n");
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append("\\n");
+                prev = i + 1;
                 break;
             case '\f':
-                w.write("\\f");
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append("\\f");
+                prev = i + 1;
                 break;
             case '\r':
-                w.write("\\r");
+                if(prev < i) {
+                    w.append(string, prev, i);
+                }
+                w.append("\\r");
+                prev = i + 1;
                 break;
             default:
                 if (c < ' ' || (c >= '\u0080' && c < '\u00a0')
                         || (c >= '\u2000' && c < '\u2100')) {
-                    w.write("\\u");
+                    if(prev < i) {
+                        w.append(string, prev, i);
+                    }
                     hhhh = Integer.toHexString(c);
-                    w.write("0000", 0, 4 - hhhh.length());
-                    w.write(hhhh);
-                } else {
-                    w.write(c);
+                    w.append("\\u0000", 0, 6 - hhhh.length());
+                    w.append(hhhh);
+                    prev = i + 1;
                 }
             }
         }
-        w.write('"');
+        if(prev == 0) {
+            w.append(string);
+        } else if(prev < len) {
+            w.append(string, prev, len);
+        }
+        w.append('"');
         return w;
     }
 
@@ -1699,10 +1728,8 @@ public String toString() {
      *             If the object contains an invalid number.
      */
     public String toString(int indentFactor) throws JSONException {
-        StringWriter w = new StringWriter();
-        synchronized (w.getBuffer()) {
-            return this.write(w, indentFactor, 0).toString();
-        }
+        StringBuilder w = new StringBuilder();
+        return this.write(w, indentFactor, 0).toString();
     }
 
     /**
@@ -1730,40 +1757,7 @@ public String toString(int indentFactor) throws JSONException {
      *             If the value is or contains an invalid number.
      */
     public static String valueToString(Object value) throws JSONException {
-        if (value == null || value.equals(null)) {
-            return "null";
-        }
-        if (value instanceof JSONString) {
-            Object object;
-            try {
-                object = ((JSONString) value).toJSONString();
-            } catch (Exception e) {
-                throw new JSONException(e);
-            }
-            if (object instanceof String) {
-                return (String) object;
-            }
-            throw new JSONException("Bad value from toJSONString: " + object);
-        }
-        if (value instanceof Number) {
-            return numberToString((Number) value);
-        }
-        if (value instanceof Boolean || value instanceof JSONObject
-                || value instanceof JSONArray) {
-            return value.toString();
-        }
-        if (value instanceof Map) {
-            Map<?, ?> map = (Map<?, ?>) value;
-            return new JSONObject(map).toString();
-        }
-        if (value instanceof Collection) {
-            Collection<?> coll = (Collection<?>) value;
-            return new JSONArray(coll).toString();
-        }
-        if (value.getClass().isArray()) {
-            return new JSONArray(value).toString();
-        }
-        return quote(value.toString());
+        return writeValue(new StringBuilder(), value).toString();
     }
 
     /**
@@ -1828,14 +1822,23 @@ public static Object wrap(Object object) {
      * @return The writer.
      * @throws JSONException
      */
-    public Writer write(Writer writer) throws JSONException {
+    public <T extends Appendable> T write(T writer) throws JSONException {
         return this.write(writer, 0, 0);
     }
 
-    static final Writer writeValue(Writer writer, Object value,
+    static <T extends Appendable> T writeValue(T writer, Object value)
+            throws JSONException {
+        try {
+            return writeValue(writer, value, 0 ,0);
+        } catch (IOException e) {
+            throw new JSONException(e);
+        }
+    }
+
+    static final <T extends Appendable> T writeValue(T writer, Object value,
             int indentFactor, int indent) throws JSONException, IOException {
         if (value == null || value.equals(null)) {
-            writer.write("null");
+            writer.append("null");
         } else if (value instanceof JSONObject) {
             ((JSONObject) value).write(writer, indentFactor, indent);
         } else if (value instanceof JSONArray) {
@@ -1849,26 +1852,30 @@ static final Writer writeValue(Writer writer, Object value,
         } else if (value.getClass().isArray()) {
             new JSONArray(value).write(writer, indentFactor, indent);
         } else if (value instanceof Number) {
-            writer.write(numberToString((Number) value));
+            writer.append(numberToString((Number) value));
         } else if (value instanceof Boolean) {
-            writer.write(value.toString());
+            writer.append(value.toString());
         } else if (value instanceof JSONString) {
-            Object o;
+            String o;
             try {
                 o = ((JSONString) value).toJSONString();
             } catch (Exception e) {
                 throw new JSONException(e);
             }
-            writer.write(o != null ? o.toString() : quote(value.toString()));
+            if (o != null) {
+                writer.append(o);
+            } else {
+                quote(value.toString(), writer);
+            }
         } else {
             quote(value.toString(), writer);
         }
         return writer;
     }
 
-    static final void indent(Writer writer, int indent) throws IOException {
+    static final <T extends Appendable> void indent(T writer, int indent) throws IOException {
         for (int i = 0; i < indent; i += 1) {
-            writer.write(' ');
+            writer.append(' ');
         }
     }
 
@@ -1887,47 +1894,47 @@ static final void indent(Writer writer, int indent) throws IOException {
      * @return The writer.
      * @throws JSONException
      */
-    public Writer write(Writer writer, int indentFactor, int indent)
+    public <T extends Appendable> T write(T writer, int indentFactor, int indent)
             throws JSONException {
         try {
             boolean commanate = false;
             final int length = this.length();
             Iterator<String> keys = this.keys();
-            writer.write('{');
+            writer.append('{');
 
             if (length == 1) {
-                Object key = keys.next();
-                writer.write(quote(key.toString()));
-                writer.write(':');
+                String key = keys.next();
+                quote(key, writer);
+                writer.append(':');
                 if (indentFactor > 0) {
-                    writer.write(' ');
+                    writer.append(' ');
                 }
                 writeValue(writer, this.map.get(key), indentFactor, indent);
             } else if (length != 0) {
                 final int newindent = indent + indentFactor;
                 while (keys.hasNext()) {
-                    Object key = keys.next();
+                    String key = keys.next();
                     if (commanate) {
-                        writer.write(',');
+                        writer.append(',');
                     }
                     if (indentFactor > 0) {
-                        writer.write('\n');
+                        writer.append('\n');
                     }
                     indent(writer, newindent);
-                    writer.write(quote(key.toString()));
-                    writer.write(':');
+                    quote(key, writer);
+                    writer.append(':');
                     if (indentFactor > 0) {
-                        writer.write(' ');
+                        writer.append(' ');
                     }
                     writeValue(writer, this.map.get(key), indentFactor, newindent);
                     commanate = true;
                 }
                 if (indentFactor > 0) {
-                    writer.write('\n');
+                    writer.append('\n');
                 }
                 indent(writer, indent);
             }
-            writer.write('}');
+            writer.append('}');
             return writer;
         } catch (IOException exception) {
             throw new JSONException(exception);
diff --git a/JSONString.java b/JSONString.java
index 1f2d77dd1..26f8601aa 100644
--- a/JSONString.java
+++ b/JSONString.java
@@ -1,4 +1,29 @@
 package org.json;
+
+/*
+Copyright (c) 2002 JSON.org
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+The Software shall be used for Good, not Evil.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
 /**
  * The <code>JSONString</code> interface allows a <code>toJSONString()</code>
  * method so that a class can change the behavior of
@@ -6,13 +31,25 @@
  * and <code>JSONWriter.value(</code>Object<code>)</code>. The
  * <code>toJSONString</code> method will be used instead of the default behavior
  * of using the Object's <code>toString()</code> method and quoting the result.
+ * <p>
+ * If <code>toJSONString()</code> returns <code>null</code>, the class's
+ * <code>toString()</code> value will be quoted and used.</p>
+ * 
+ * @author json.org
+ * @version 2016-07-28
  */
 public interface JSONString {
     /**
      * The <code>toJSONString</code> method allows a class to produce its own JSON
-     * serialization.
+     * serialization. If <code>null</code> is returned, the class's
+     * <code>toString</code> method will be called, and the result will be
+     * quoted and used.
+     * <p>
+     * If a runtime exception is thrown, this will be caught and propagated
+     * as a <code>JSONException</code>.</p>
      *
-     * @return A strictly syntactically correct JSON text.
+     * @return A strictly syntactically correct JSON text, or <code>null</code>
+     * to indicate the <code>toString</code> value should be used instead
      */
     public String toJSONString();
 }
diff --git a/JSONStringer.java b/JSONStringer.java
index 5fbc96a9a..056913373 100644
--- a/JSONStringer.java
+++ b/JSONStringer.java
@@ -24,8 +24,6 @@ of this software and associated documentation files (the "Software"), to deal
 SOFTWARE.
 */
 
-import java.io.StringWriter;
-
 /**
  * JSONStringer provides a quick and convenient way of producing JSON text.
  * The texts produced strictly conform to JSON syntax rules. No whitespace is
@@ -54,14 +52,14 @@ of this software and associated documentation files (the "Software"), to deal
  * <p>
  * This can sometimes be easier than using a JSONObject to build a string.
  * @author JSON.org
- * @version 2015-12-09
+ * @version 2016-07-28
  */
 public class JSONStringer extends JSONWriter {
     /**
      * Make a fresh JSONStringer. It can be used to build one JSON text.
      */
     public JSONStringer() {
-        super(new StringWriter());
+        super(new StringBuilder());
     }
 
     /**
diff --git a/JSONWriter.java b/JSONWriter.java
index 09d113030..ea5b06fd4 100644
--- a/JSONWriter.java
+++ b/JSONWriter.java
@@ -1,7 +1,6 @@
 package org.json;
 
 import java.io.IOException;
-import java.io.Writer;
 
 /*
 Copyright (c) 2006 JSON.org
@@ -50,11 +49,11 @@ of this software and associated documentation files (the "Software"), to deal
  * <p>
  * The first method called must be <code>array</code> or <code>object</code>.
  * There are no methods for adding commas or colons. JSONWriter adds them for
- * you. Objects and arrays can be nested up to 20 levels deep.
+ * you. Objects and arrays can be nested up to 200 levels deep.
  * <p>
  * This can sometimes be easier than using a JSONObject to build a string.
  * @author JSON.org
- * @version 2015-12-09
+ * @version 2016-08-04
  */
 public class JSONWriter {
     private static final int maxdepth = 200;
@@ -88,12 +87,12 @@ public class JSONWriter {
     /**
      * The writer that will receive the output.
      */
-    protected Writer writer;
+    protected Appendable writer;
 
     /**
      * Make a fresh JSONWriter. It can be used to build one JSON text.
      */
-    public JSONWriter(Writer w) {
+    public JSONWriter(Appendable w) {
         this.comma = false;
         this.mode = 'i';
         this.stack = new JSONObject[maxdepth];
@@ -102,7 +101,7 @@ public JSONWriter(Writer w) {
     }
 
     /**
-     * Append a value.
+     * Append a JSON-encoded value.
      * @param string A string value.
      * @return this
      * @throws JSONException If the value is out of sequence.
@@ -114,9 +113,9 @@ private JSONWriter append(String string) throws JSONException {
         if (this.mode == 'o' || this.mode == 'a') {
             try {
                 if (this.comma && this.mode == 'a') {
-                    this.writer.write(',');
+                    this.writer.append(',');
                 }
-                this.writer.write(string);
+                this.writer.append(string);
             } catch (IOException e) {
                 throw new JSONException(e);
             }
@@ -129,6 +128,35 @@ private JSONWriter append(String string) throws JSONException {
         throw new JSONException("Value out of sequence.");
     }
 
+    /**
+     * Append a value, converting it into a JSON string.
+     *
+     * @param val A value.
+     * @return this
+     * @throws JSONException If the value is out of sequence.
+     */
+    private JSONWriter appendValue(Object val) throws JSONException {
+        try {
+            switch (this.mode) {
+                case 'a':
+                    if (this.comma) {
+                        this.writer.append(',');
+                    }
+                    break;
+                case 'o':
+                    this.mode = 'k';
+                    break;
+                default:
+                    throw new JSONException("Value out of sequence.");
+            }
+            JSONObject.writeValue(this.writer, val);
+            this.comma = true;
+            return this;
+        } catch (IOException e) {
+            throw new JSONException(e);
+        }
+    }
+
     /**
      * Begin appending a new array. All values until the balancing
      * <code>endArray</code> will be appended to this array. The
@@ -163,7 +191,7 @@ private JSONWriter end(char mode, char c) throws JSONException {
         }
         this.pop(mode);
         try {
-            this.writer.write(c);
+            this.writer.append(c);
         } catch (IOException e) {
             throw new JSONException(e);
         }
@@ -207,10 +235,10 @@ public JSONWriter key(String string) throws JSONException {
             try {
                 this.stack[this.top - 1].putOnce(string, Boolean.TRUE);
                 if (this.comma) {
-                    this.writer.write(',');
+                    this.writer.append(',');
                 }
-                this.writer.write(JSONObject.quote(string));
-                this.writer.write(':');
+                JSONObject.quote(string, this.writer);
+                this.writer.append(':');
                 this.comma = false;
                 this.mode = 'o';
                 return this;
@@ -300,7 +328,7 @@ public JSONWriter value(boolean b) throws JSONException {
      * @throws JSONException If the number is not finite.
      */
     public JSONWriter value(double d) throws JSONException {
-        return this.value(new Double(d));
+        return this.append(JSONObject.numberToString(Double.valueOf(d)));
     }
 
     /**
@@ -322,6 +350,6 @@ public JSONWriter value(long l) throws JSONException {
      * @throws JSONException If the value is out of sequence.
      */
     public JSONWriter value(Object object) throws JSONException {
-        return this.append(JSONObject.valueToString(object));
+        return this.appendValue(object);
     }
 }