Resource ReSerVation Protocol (RSVP) was developed as an intended key component for the evolving Internet, and in particular for the Integrated Services architecture. Therefore, RSVP performance is crucially important; yet this has been little studied up till now. In this paper, we target two of the most important aspects of RSVP: its ability to establish flows and its steady-state overhead. We first identify the factors influencing the performance of the protocol by modelling the establishment mechanism. Then, we propose the principles of a Fast Establishment Mechanism (FEM) aimed at speeding up the set-up procedure in RSVP. We analyse FEM by means of simulation, and show that it offers improvements to the performance of RSVP over a range of likely circumstances. We also present the principles of a simple mechanism aimed at reducing the steady-state (i.e. refresh) message overhead of RSVP.