For mixed-criticality systems, safety standards (e.g. ISO 26262) require sufficient independence among different criticality levels, unless the entire system is certified according to the highest applicable level. We present a resource arbitration scheme that provides sufficient independence among different criticality levels w.r.t. timing properties. We exploit throughput and latency slack of critical applications by prioritizing non-critical over critical accesses and only switching priorities when necessary. By using an accurate representation of resource access patterns and workloads, the proposed arbitration scheme achieves an improved resource utilization compared to classical approaches that use simple access counters. The approach allows to provide service guarantees for critical applications, while reducing the adverse effects through strict prioritization on non-critical applications.