While investigating a problem my profiler showed up a large amount of String creations. I figured that cause was located in AppendableWriter as it uses an Appendable to write the data.
However often (at least I haven't found a different scenario) the Appendable instance was a Writer itself, so the creation of a String using "new String(..)" basically isn't necessary in most cases.
My patch tests whether the Appendable is a Writer and then uses this Writer directly.