I found there is a a scope of optimizing the code, over initialize() if we have compressionCodecs & codec instantiated only if its a compressed input.
Mean while Gelesh George Omathil, added if we could avoid the null check of key & value. This would time save, since for every next key value generation, null check is done. The intention being to instantiate only once and avoid NPE as well. Hope both could be met if initialize key & value over initialize() method. We both have worked on it.