This paper describes new and improved techniques which help a unification-based parser to process input efficiently and robustly. In combination these methods result in a speed-up in parsing time of more than an order of magnitude. The methods are correct in the sense that none of them rule out legal rule applications. and Sch~ifer, 1994; Krieger and Sch~ifer, 1995) and an advanced agenda-based bottom-up chart parser (Kiefer and Scherf, 1996).