I'm not sure this looks at the correct resources. If I read TFA, they have an IPC of 0.85 on the benchmark, but a theoretical IPC limit of 6. So 50% usage wou

I'm not sure this looks at the correct resources. If I read TFA, they have an IPC of 0.85 on the benchmark, but a theoretical IPC limit of 6. So 50% usage would be IPC=3, a lot better than the benchmark. So execution resources aren't the bottleneck. Also, this analysis skips the easily predictable jumps like loops. I remember 90% prediction being relatively easy to reach in most programs just because of loops. A better way would be to let the predictor not only respond with taken/not taken, but also with high/low confidence. If confidence us low, then a CPU could spend some unused part of IPC. All of this probably wont work in practice, of course.