Try this for lag issue

skywave

try to open all content, i mean inside store and i open it and check every weapon, wait until download properly, same with craft, base defense, clan, pvp, campaign, OPEN EVERY SINGLE CONTENT OF THIS GAME. and you will be good when play pvp, and much much much better and smooth ( like new player with no lag issue ) .
ipad mini 2
ios 8.4

already 15x play pvp with no lag issue again.