Wont help you any if the CPU is a problem. Which it can be because of a ton of reasons. Wont help you either with streaming issues, because streaming from Blu Ray is a pain in the ass.
Take AC Unity. THat game has prebacked lighting. The CPU has to decompress and handle that data, Just one of many examples.
And Wii U's CPU is weak. It's not a dumb desing (CELL was, basically brute force), but terribly slow. Jaguar in PS4/Xone has arround 103/115 GFLOP/s.
WiiU's CPU is somewhere between 10 and 15 GFLOP/s. Should be more in the 15GFLOP/s direction if it scales perfectly with clock speed and number of cores.
So that is basically seven times slower than PS4 CPU and almost 8 times slower than Xbox Ones CPU.
Wii U's GPU is, best guess, a cut down AMD Redwood like in the Radeon 5550. Just not with deaactivated units. That's not that bad. The CPU can become a real bottleneck though.