A garbage collection system that needs to meet real-time requirements utilizes a read barrier that is implemented in an optimizing compiler. The read barrier is implemented with a forwarding pointer positioned in a header of each object. The forwarding pointer points to the object unless the object has been moved. The barrier is optimized by breaking the barrier and applying barrier sinking to sink the read barrier to its point of use and by using sub-expression elimination. A null-check for the read barrier is combined with a null-check required by the real-time application. All objects are located and moved with the collector to minimize variations in mutator utilization.