When I install iOS 11.3 my iPhone 6s puls could start hanging and it slow day by day , even its camera its not working properly:(

When I upgrade my software 11.2 to 11.3 it could start hanging and slow day by day 😟 it’s not good for apple fan because everyone got his/her iPhone by saving his/her salary 😟 when I collect me money for vough an iPhone 6s it could be take a 3 years because I’m a craziest fan ever no one crazy like me , I remember when I bought my iPhone I cannot sleep for next 2 Days in just iPhon happiness *_* but now its not work properly I don’t have enough money bought iPhone 8plu 😟 kindle corretc your next version and it would be work on iPhone 6s Plus