diff --git "a/C:\\Users\\LAZARI~1\\AppData\\Local\\Temp\\str8D7C.c" "b/P:\\ri\\sandbox\\rb193\\string.c"
index 711918b..69c6486 100644
--- "a/C:\\Users\\LAZARI~1\\AppData\\Local\\Temp\\str8D7C.c"
+++ "b/P:\\ri\\sandbox\\rb193\\string.c"
@@ -406,10 +406,58 @@ str_new(VALUE klass, const char *ptr, long len)
     return str;
 }
 
+/* use class-variable (bit-flag) */
+#define FL_CALL_INIT FL_USER18
+
+VALUE
+rb_str_method_added(VALUE self, VALUE method_symbol)
+{
+/*  callback method, called whenever a String class method is added (defined) */
+
+    ID mid = SYM2ID(method_symbol);
+    ID idInitialize = rb_intern("initialize");
+
+    if (mid == idInitialize) {
+	FL_SET(rb_cString, FL_CALL_INIT);
+    }
+    return Qtrue; /* unused */
+}
+
+VALUE
+rb_str_method_undefined(VALUE self, VALUE method_symbol)
+{
+/*  callback method, called whenever a String class method is undefined */
+
+    if ( SYM2ID(method_symbol) == rb_intern("initialize") ) {
+	FL_UNSET(rb_cString, FL_CALL_INIT);
+    }
+    return Qtrue; /* unused */
+}
+
+VALUE
+rb_str_method_removed(VALUE self, VALUE method_symbol)
+{
+/*  callback method, called whenever a String class method is removed */
+
+    if ( SYM2ID(method_symbol) == rb_intern("initialize") ) {
+	FL_UNSET(rb_cString, FL_CALL_INIT);
+    }
+    return Qtrue; /* unused */
+}
+
 VALUE
 rb_str_new(const char *ptr, long len)
 {
-    return str_new(rb_cString, ptr, len);
+    /* str is already initialized by original initialize within str_new() */
+    VALUE str = str_new(rb_cString, ptr, len);
+
+    /* speed: call initialize only if it was redefined. See #4893 */
+    if (FL_TEST(rb_cString, FL_CALL_INIT)) {
+	/* passing str itself as parameter, avoiding need for a temp str */
+	rb_obj_call_init((VALUE)str, 1, &str);
+    }
+
+    return str;
 }
 
 VALUE
@@ -7724,6 +7772,11 @@ Init_String(void)
     rb_cString  = rb_define_class("String", rb_cObject);
     rb_include_module(rb_cString, rb_mComparable);
     rb_define_alloc_func(rb_cString, str_alloc);
+
+    rb_define_singleton_method(rb_cString, "method_added", rb_str_method_added, 1);
+    rb_define_singleton_method(rb_cString, "method_undefined", rb_str_method_undefined, 1);
+    rb_define_singleton_method(rb_cString, "method_removed", rb_str_method_removed, 1);
+
     rb_define_singleton_method(rb_cString, "try_convert", rb_str_s_try_convert, 1);
     rb_define_method(rb_cString, "initialize", rb_str_init, -1);
     rb_define_method(rb_cString, "initialize_copy", rb_str_replace, 1);