Hexxit lag help

[Froobz]

Basically I'm playing hexxit happily and after like 10-15 mins it goes SUPER laggy to the point of not playing BUT I went in twilight forest just before and it wasn't laggy at all I was there for a while and as soon as I come back through portal it's back to laggy. In my task manager my memory is 99% BUT on the world there's nothing at my house it's literally a cave with a few chests