Performance improvement. Switching from looping through a doubled array to using a Map. This probably costs more for simple cases like Java/EcmaScript/Xml, but makes up for it in the Html case. This gets performance of the testUnescapeHexCharsHtml method back down to near the same region as the original code
commons/proper/lang/trunk/src/java/org/apache/commons/lang/text/translate/LookupTranslator.java