Was a pile of shit for me too.
I reset my console. I don't mean on and off. I held the button on the console down till it shut down. I restarted it and voilà. Works well.
Well... it's far from perfect still. 343 has a lot of work to do. It's faster. But definitely not Call of Duty search times. That's a pipe dream. Anyway, this worked for me. Not guaranteed.
Still... 343 messed this one up. I'm sure it wasn't easy getting 4 games working with their own code and all so I still have complete faith in Halo 5. I bet the beta will run better than this. Anyway, back to Halo :) see you online... hopefully.