As it was mentioned earlier in the thread, the WiiU's CPU is not exactly up to scratch. In fact, it's technology far "older" than 7 years old - it's literally just three Broadway cores with some alterations (Out-of-Order processing) strapped together at a higher frequency - the CPU inherited most of the flaws that plagued both the Wii and the Gamecube. Nintendo put a lot of pressure on GPGPU, but not all studios are willing to go in that direction yet and demand a little more from processors - the little more that the WiiU doesn't give.
Of course there are no accurate benchmarks of the CPU itself, nobody really knows its performance. Technically it has more threads-per-core, but we won't how far you can push it without some benchmarking software running on the console itself.