The phenomenon of plasmonic resonance has been identified in recent times as a means of breaking the diffraction limit that hinders high performance lithography systems in use today. Experimental results based on interleaved silver and dielectric layers have shown that resolution as low as /6 can be achieved and that ‘superlenses’ are indeed realisable. However, examples of ‘perfect’ lenses, predicted to have true, diffraction-free performance, have yet to be fabricated. This paper uses numerical models of silver-dielectric superlenses to explore performance around and beyond the diffraction limit, examining different superlens designs and the reasons behind their specific performance enhancements and limitations.