Persistent_BNDC (P_BNDC, for short) is a security property for processes in dynamic contexts, i.e., contexts that can be reconfigured at runtime.We study how to efficiently decide if a process is P_BNDC.We exploit a characterization of P_BNDC through a suitable notion of Weak Bisimulation up to high level actions. In the case of finite-state processes, we study two methods for computing the largest weak bisimulation up to high level actions: (1) via Characteristic Formulae and Model Checking for μ-calculus and (2) via Closure up to a set of actions and Strong Bisimulation. This second method seems to be particularly appealing: it can be performed using already existing tools at a low time complexity.