CompressingStoredFieldsReader.visitDocument (line 597) loops through the fields in the input while consulting the StoredFieldVisitor on what to do. There is a small optimization that could be done on the last loop iteration. If the visitor returns Status.NO then it should be treated as equivalent to Status.STOP. As it is now, it will call skipField() which reads needless bytes from the DataInput that won't be used.
With this optimization in place, it is advisable to put the largest text field last in sequence – something the user or search platform (e.g. ES/Solr) could do.