The bug

When the chunks load(only new chunks) the fps is going to decrease. Sometimes creating huge lag spikes when I enter the world(generating the new chunks, 1-10 fps). But when I creating a world or explore the world in creative mode I got huge fps drop. Sometimes the game freezes. In version 1.12.2 I had no such problems.

And huge lag in superflat worlds.

_________________________________________________________________________________

 Links for similar problems:

1st https://www.minecraftforum.net/forums/minecraft-java-edition/recent-updates-and-snapshots/2907052-is-it-just-my-computer-or-is-minecraft-laggy-in

2nd https://www.spigotmc.org/threads/bukkit-craftbukkit-spigot-bungeecord-1-13-pre7-development-builds.328883/page-14#post-3075276

_________________________________________________________________________________

Juho Niilekselä's video: https://youtu.be/0MxGdhDQpH8

_________________________________________________________________________________

 My recorded videos:

Video of the 1.12.2 version: https://drive.google.com/file/d/1_--VpWTSXdAx5qe42cYyXZehZwKBAogd/view?usp=sharing

Video of the 1.13 version: https://drive.google.com/file/d/1D7rE8P21D3L0o_zFf35Zb0H6P7xcLeWM/view?usp=sharing

 ________________________________________________________________________________

My friends videos of 1.13: 

https://drive.google.com/file/d/1WDS3WhGK8aLl-noUSSIXkS-Uo0RxZgcs/view?usp=sharing

(He has CPU: 4x Intel(R) Core(TM) i5-7400 CPU @ 3.00 GHz,  GeForce GTX 1050 Ti/PCIe/SSE2, java update 1.8_51 64 bit)

_________________________________________________________________________________

Useful comments:

Christian Rau's comment:

I certainly optimized my world from 1.12.2 to 1.13 and experience an overall much more laggy gameplay. There's perceivable stuttering compared to a rather smooth gameplay in 1.12.2 and it's a seemingly constant situation. And it's a rather small singleplayer world (I explicitly culled the majority of my world's chunks in preparation for 1.13).

FuturTybz's comment:

I can confirm for 1.13 release. At first, I wondered if it was because of my bad PC but apparently not. The game is very smooth when standing still but there is a huge FPS drop when loading chunks that it is almost unplayable for those who have a low-end PC. There was no such issue in 1.12.2. This problem is still present when on a 1.13 vanilla multiplayer server.

Martin Oláh's comment:

Tested it myself, it stutters and lags alot, considering my specs are pretty high so this shouldn't be happening.

• 1.13 is insanely laggy, I tried adding more ram (4gb) it fixed the issue for a while, after few minutes it stutters again
• On 1.12.2 this doesn't happen at all, gameplay is butterly smooth also with 1gb allocated.
• https://www.youtube.com/watch?v=VRkLWa1tm1s