If you want to be clean you can use the finish method on the XML::Parser::Expat object:

finish
           Unsets all handlers (including internal ones that set context), but
           expat continues parsing to the end of the document or until it
           finds an error.  It should finish up a lot faster than with the
           handlers set.

Generally, when using XML::Parser, it is worth reading the docs for XML::Parser::Expat, as a lot of very useful methods are only described there.