In this paper, the implementation of security system that has strict requirements on the time of evaluation of each transaction made by the user is examined on the example of building a system for user behaviour modelling using Markov models. Evaluation of the effectiveness of both the classical approach to the implementation of a server that calculates metric of the user model and with the use of lightweight threads, as well as of a new ideology - Deferred-based event model is performed. A number of tests of various configurations are conducted, showing the preferred server for the Deferred-based type of system as well as an approach to implementing this type of request service.