Implementations are disclosed for a simultaneous multithreading processor configured to execute a plurality of threads. In one implementation, the simultaneous multithreading processor is configured to select a first thread of the plurality of threads according to a predefined scheme, and access an instruction completion table to determine whether the first thread is eligible to have a first instruction prioritized. Responsive to determining that the first thread is eligible to have the first instruction prioritized, the simultaneous multithreading processor is further configured to execute the first instruction of the first thread using a dedicated prioritization resource.