Going to add my +1 for possible Game Centre issues.
Fairly sporadic but it certainly does seem to be an impact on playing on iOS. If I resume a session ‘in progress’ (I.e. Minimised on iPad) game centre load takes around 10-20secs. Launching the app a fresh and there can be looooonnnnggg delays before any progress or loading bars appear - as soon as the game centre prompt comes on screen then the app kicks into life and the loading bar will start/continue.
As an example, logging in this morning took 2min 8secs where the app appears to just hang, then the game centre pop up appears and it continues. N.b. This delay is before the loading bar about assets and character updates etc. So actual login time can be much longer.
Is it possible to move the game centre login piece to fire after the gems of war loading and see if this offers any improved loading times?
[I play on both an iPad Air and iPhone 5s with latest iOS.]