Hi, I´m from Argentina so my english is not that good. So if anyone read this thanks for understanding. 

I opened the game normally in survival solo and suddenly it took a while to load the world. When I got in it seems normally for the moment but then i realize the game had same issues similar as when you experiencie lag in games: mobs suddenly didn´t move anymore, i could move and the animation for choping executed but the items didn´t appear on my inventory untill the game could load properly, it take too much time to travel with portals, etc. I closed the game, opened it again, repaired it with Windows, uninstall (making a copy of my world before) and install again. Not only it didn´t work but it was even worst. Now i can bearly open the world after a really long moment of loading and it still has these kind of mistakes. I´m seeing that it performs worst every time. From Task Manager i can see that the CPU is running on 100% and RAM on 70% (17gb). Also i tried desactivating and putting all the settings down, such as chunk render, antialiasing, clouds, light, etc.

My hardware is:
Notebook Asus Tuf Fx 505
Ryzen 5 3550h
Radeon RX 560x
SSD Kingston RBUSN8154P3512GJ
24 gb of RAM

Also i'd like to mention that i'm not having issues with any other game or aplication in Windows and that these problems suddenly appeared from one day to the ohter. Two nights ago i was playing normally and yesterday, when i opened the game, the problems start to manifest. About the performance i tried with more demanding games such as Control or Watch Dogs 2 and everything worked as same as before.
I'm rookie on Minecraft, this is in fact my first world, so i think i didn't do nothing strange with the world. The last thing i was doing was create portals in nether so i can make routes. My base is approximately on X:0 Z:0, and the farest portal i created is in X:300 Z:1000 on nether. I think this shouldn´t be the problem but i mentioned it anyway.