The number of features that are supported in modern multimedia devices is increasing faster than ever. Estimating the performance of such applications when they are running on shared resources is becoming increasingly complex. Simulation of all possible use-cases is very time-consuming and often undesirable. In this paper, a new technique is proposed based on probabilistically estimating the performance of concurrently executing applications that share resources. Two different methods of employing this approach are presented and compared with state-of-the-art technique, and with achieved performance found through extensive simulations. The results are within 15% of simulation result (considered as reference case) and up to ten times better than a worst-case estimation approach. The approach scales very well with increasing number of applications, and can also be applied at run-time for admission control.