In safety-critical multi-core architectures, isolation becomes more challenging as multiple components are shared between the cores, which generates delays in execution time. To reduce buses contention, the bandwidth allocated to each application must be limited. State-of-the-art solutions for bus budgeting allocation are not scalable and do not provide enought flexibility to model complex systems. We propose a novel heuristic for bus budget allocation. We achieve scalable execution times up to 45 times faster compared to the state-of-the-art. We introduce real-life constraints such as application dependencies, mapping and release time. which make our approach applicable in complex systems.