Help Android 5.1.1 bug in samsung e7

[Nagasai]

Hi there!
I have purchased samsung galaxy e7 four months ago.It had no problem upto last week I have upgraded it this week to lollipop5.1.1 .The smart task manager isn't responding correctly and all my documents are also opening very slowly as compared to my kitkat version and my device is getting too hot which i have not noticed in 4.4.4kitkat.please give me some suggestion to help me.

 

[Pugs1957]

After a major update it's usually a good idea to do a factory reset although sometimes wiping system cache can do the trick