XACML (eXtensible Access Control Markup Language) is an XML-based language for access control that has been standardized in OASIS. In this language, any entities involved in access control (i.e. users, resources, actions and environment) are specified by a set of attributes. This specification also includes the description of an architecture that explains how the policy decision point (PDP) retrieves the needed attributes values when it evaluates the policy to take its authorization decision.

In this paper, we show this approach for getting the attributes values is a bottleneck to the performance of the authorization decision-making-process for attributes whose process for retrieving the value is long and the changing of its value doesn?t impact the policy frequently. Thus, we propose an improvement of the XACML architecture in order to accelerate the decision-making-process when PDP has to treat such kind of attributes.