Nexus 5X and Nexus 6 lagging in games and certain applications.

I don't know why but previous to having the Galaxy S6 I had the Nexus 6. It has serious issues playing Puzzles and Dragons without lagging. I also had issues with Brave Frontier. I don't understand why. It's hardware was plenty capable from what I understand. This was without Encryption. Fast forward to now. I've had my N5X for a few days and am just now getting around to setting it up. I've rooted, removed encryption and BL unlock. The phone is blazing fast... until I decide to play a game. Puzzles and Dragons and Brave Frontier are STILL laggy as all get out. What's the deal? They work flawlessly on the Galaxy S6. If this is going to be an ongoing trend I may need to send the N5X back and stick with the Galaxy S6. This is incredibly frustrating.

Applications and Feature functionality

As far as I am aware, there is only chinese versions of the mobile available... and for that reason, I have some questions.
1) Do all of the applications change and function in English once the language is changed from Chinese (Will I ever see chinese if I change it to English?)
2) Does the bloatware effect the running/battery/etc. of the phone?
3) Can I see some sample pictures using the front and back camera?
4) Does it have any protection over the glass on the front? (e.g. Corning Gorilla, etc.)
and
5) Which website is the best to purchase it from to ship to Australia?

Thankyou.