Hi. I've noticed that DefaultStyledDocument has a slowness issue when inserting text. Even if you subclass it and expose the faster method: protected void insert(int offset, ElementSpec[] data)
the body of the method still uses a stringbuilder to append all char[] inside of the data before actually inserting into the content. This is because the only method for insertion in the default content interface is: public UndoableEdit insertString(int where, String str) Now if there are going to be extension methods in java 8, it would be nice to have a public UndoableEdit insert(int where, int index, int length, char[] str) default { return insert(where, new String(index, length, str); } with a adequate specialization in GapContent (that obviously doesn't call the string version), and that that new method is used in the protected void insert(int offset, ElementSpec[] data) method (and where it makes sense)