U shouldn't need game centre 4 achievement

Do you guys have problems with it jamming up a lot, and when you type it suffers serious lag? That's what I've been experiencing 

yes i usually restart it every hour and its ok

This is a big problem for me. My game center is linked to HK, however my HK account says it cannot be linked to my game center account. I'm not sure the reasoning behind HK's stance on changing game center accounts, however I would like to see it changed.