Drop of almost 80 fps when inside a home or looking at a block.

I have a few friends that have also had this issue so its not just my pc. Whenever i am outside looking up my fps jumps to 100+ however when i go back in my house or look at any block like grass or wood etc it drops to 20- 40 fps. This is odd as i never had this issue before not sure whats causing it or how to fix just didn't see it posted here at all and figured maybe someone would know whats up.