Q: iphone 6 gets hanged while using hike, real racing and such common apps

I WAS GIFTED AN IPHONE 6 64 GB AT MY 18TH BIRTHDAY BY MY DAD LAST MARCH. ALL SEEMED TO BE WORKING F9. BUT THESE DAYS MY IPHONE ISNT DOING GOOD. I EXPERIENCE IT HANGING ONCE IN A WHILE. IT GETS HANGED ON ALL COMMON APPS SUCH AS HIKE, REAL RACING, SHADOW FIGHT 2 AND MANY OTHER SUCH APPS. WHILE TALKING TO FRIENDS ON HIKE I EXPERIENCED MY TYPING SPEED TO BE FASTER THAN ACCEPTING SPEED OF MY IPHONE, FIRST I THOUGHT MAYBE I HAD ENHANCED TYPING SKILLS BUT THAT IS NOT THE CASE. MY IPHONE HAS GONE ALL THE MORE SLOW AND THAT IS PECULIAR FOR AN IPHONE WITH 64 GB INTERNAL MEMORY AND A8 CHIPSET. AS IT HAS NOT BEEN A YEAR SINCE I BOUGHT MY PHONE I WANT A PERMANENT SOLUTION OR I WANT MY PHONE TO BE REPLACED.