My character and screen stop and have sudden low fps but the world keeps moving forward

My world has since the previous version, when installing this one it started to have low fps and "Stucks", the screen and my character stop but the world continues to advance (I can't even pass it) It's caused even a simple zombie to kill me. I have so much for this world that I don't want to lose it. Please fix this bug. Thank you for your attention. These jerks last 4-10 seconds!!!!!! I'm mid-range and still. Help, help!