Markovian Process Algebras approximate their model of synchronisation events in order to preserve their Markovian nature. This paper investigates synchronisation models in a stochastic context and focuses on how the Markovian approximation of synchronisation affects the accuracy of the performance model. TIPP and PEPA are used as specific cases throughout, and their different methods of synchronisation are compared for effectiveness in performance modelling. The paper ends with a generally distributed example of real-world synchronisation, which we are able to solve analytically and then approximately with four Markovian Process Algebra models. From the results of this analysis, we show how such approximation affects the accuracy of the performance model of TIPP and PEPA.