Screen quality seems to have dropped in games since 5.1.1

Hi, I have just upgraded my 12.1 last night to 5.1.1 , since updating i have noticed 2 things with 2 games i play:

Clash Of Clans - Quality of the screen looks a little less in the game than it was plus when i start the game i get like a white streak at the very bottom of my screen and then the game starts afterwards.

Boom Beach - The quality of the graphics in this game looks much worse than it did before, i have checked that the quality was still set to high which it was, things just dont look sharp like they did before.

Is there something they have done in 5.1.1 to make the tablet cope with games better by reducing the quality or something?

Any advice?

Regards

James