I have two bug reports . 1. Loading of worlds chunks etc. 2 Sever lag

Hello. I want to report two bugs that i have seen . 1. Loading of worlds chunks nad entering the nether takes a long time and this did not happen before . It is not a bug but still this needs to be fix i have to wait for the chunks to load , for the world to create and takes a long time . 2 severe lag - i cant play with this much lag and low fps . Mobs kill me before i even reach them because of lag . Please fix this lag problem . I hope you focus on these problems and make minecraft a better place . THANK YOU.