1. A method of operating a processor, the method comprising: fetching, by a fetcher instructions from an instruction source to provide an instruction stream that includes fetched branch instructions; storing, by a branch instruction queue, a plurality of fetched branch instructions from the instruction stream; speculatively executing, by a branch execution unit, fetched branch instructions by using branch prediction information and resolving whether or not a branch in each fetched branch instruction is taken, thus providing executed branch instructions; storing, by a confidence storage memory, confidence information describing an amount of confidence in the branch prediction information for the fetched branch instructions stored in the branch instruction queue; and throttling, by a throttle circuit, the fetching of instructions from the instruction source if the confidence information indicates confidence less than a predetermined confidence threshold, wherein the throttling reduces power consumption by the processor.