diff --git a/gson/src/main/java/com/google/gson/stream/JsonWriter.java b/gson/src/main/java/com/google/gson/stream/JsonWriter.java
index 42f9e899..c0e14540 100644
--- a/gson/src/main/java/com/google/gson/stream/JsonWriter.java
+++ b/gson/src/main/java/com/google/gson/stream/JsonWriter.java
@@ -122,6 +122,38 @@ import java.util.List;
  */
 public class JsonWriter implements Closeable {
 
+  /*
+   * From RFC 4627, "All Unicode characters may be placed within the
+   * quotation marks except for the characters that must be escaped:
+   * quotation mark, reverse solidus, and the control characters
+   * (U+0000 through U+001F)."
+   *
+   * We also escape '\u2028' and '\u2029', which JavaScript interprets as
+   * newline characters. This prevents eval() from failing with a syntax
+   * error. http://code.google.com/p/google-gson/issues/detail?id=341
+   */
+  private static final String[] REPLACEMENT_CHARS;
+  private static final String[] HTML_SAFE_REPLACEMENT_CHARS;
+  static {
+    REPLACEMENT_CHARS = new String[128];
+    for (int i = 0; i <= 0x1f; i++) {
+      REPLACEMENT_CHARS[i] = String.format("\\u%04x", (int) i);
+    }
+    REPLACEMENT_CHARS['"'] = "\\\"";
+    REPLACEMENT_CHARS['\\'] = "\\\\";
+    REPLACEMENT_CHARS['\t'] = "\\t";
+    REPLACEMENT_CHARS['\b'] = "\\b";
+    REPLACEMENT_CHARS['\n'] = "\\n";
+    REPLACEMENT_CHARS['\r'] = "\\r";
+    REPLACEMENT_CHARS['\f'] = "\\f";
+    HTML_SAFE_REPLACEMENT_CHARS = REPLACEMENT_CHARS.clone();
+    HTML_SAFE_REPLACEMENT_CHARS['<'] = "\\u003c";
+    HTML_SAFE_REPLACEMENT_CHARS['>'] = "\\u003e";
+    HTML_SAFE_REPLACEMENT_CHARS['&'] = "\\u0026";
+    HTML_SAFE_REPLACEMENT_CHARS['='] = "\\u003d";
+    HTML_SAFE_REPLACEMENT_CHARS['\''] = "\\u0027";
+  }
+
   /** The output data, containing at most one top-level array or object. */
   private final Writer out;
 
@@ -482,72 +514,33 @@ public class JsonWriter implements Closeable {
   }
 
   private void string(String value) throws IOException {
+    String[] replacements = htmlSafe ? HTML_SAFE_REPLACEMENT_CHARS : REPLACEMENT_CHARS;
     out.write("\"");
-    for (int i = 0, length = value.length(); i < length; i++) {
+    int last = 0;
+    int length = value.length();
+    for (int i = 0; i < length; i++) {
       char c = value.charAt(i);
-
-      /*
-       * From RFC 4627, "All Unicode characters may be placed within the
-       * quotation marks except for the characters that must be escaped:
-       * quotation mark, reverse solidus, and the control characters
-       * (U+0000 through U+001F)."
-       *
-       * We also escape '\u2028' and '\u2029', which JavaScript interprets as
-       * newline characters. This prevents eval() from failing with a syntax
-       * error. http://code.google.com/p/google-gson/issues/detail?id=341
-       */
-      switch (c) {
-      case '"':
-      case '\\':
-        out.write('\\');
-        out.write(c);
-        break;
-
-      case '\t':
-        out.write("\\t");
-        break;
-
-      case '\b':
-        out.write("\\b");
-        break;
-
-      case '\n':
-        out.write("\\n");
-        break;
-
-      case '\r':
-        out.write("\\r");
-        break;
-
-      case '\f':
-        out.write("\\f");
-        break;
-
-      case '<':
-      case '>':
-      case '&':
-      case '=':
-      case '\'':
-        if (htmlSafe) {
-          out.write(String.format("\\u%04x", (int) c));
-        } else {
-          out.write(c);
+      String replacement;
+      if (c < 128) {
+        replacement = replacements[c];
+        if (replacement == null) {
+          continue;
         }
-        break;
-
-      case '\u2028':
-      case '\u2029':
-        out.write(String.format("\\u%04x", (int) c));
-        break;
-
-      default:
-        if (c <= 0x1F) {
-          out.write(String.format("\\u%04x", (int) c));
-        } else {
-          out.write(c);
-        }
-        break;
+      } else if (c == '\u2028') {
+        replacement = "\\u2028";
+      } else if (c == '\u2029') {
+        replacement = "\\u2029";
+      } else {
+        continue;
       }
+      if (last < i) {
+        out.write(value, last, i - last);
+      }
+      out.write(replacement);
+      last = i + 1;
+    }
+    if (last < length) {
+      out.write(value, last, length - last);
     }
     out.write("\"");
   }