Okay everyone I have been doing some network probing on the Wii U and I have found a particular protocol that the Wii U uses that is quite interesting and possibly the reason the system locks up and occasionally freezes for some users, it could even be responsible for the slow menu loading times.
The good news is that this can be fixed by both you and Nintendo, all you have to do is create a rule in your wireless router, now the reason I'm posing this early is so I can get some testers as I need to test this on a larger scale.
The issue looks to be occurring from a port getting blocked that should really be open, this port is 9103 this port relates is an udp port and needs to be open, this port relates to the bacula-sd protocol that is possibly to do with user accounts on the system and sending game data information back to Nintendo, I think either way it needs to be opened up, the best way to do this is to create a rule that opens ports 1000 to 44063 in your routers port forwarding settings exclusively for the Wii U's IP address.
Apparently the DMZ setting that should allow this normally, fails to open this port and I believe that this is where the issue is occurring with the slow downs and crashes.
So if you test this out and let me know your results I will be most grateful, and here is hoping some of you have a smoother Wii U experience with this new information.