BBLZ

Haven't checked last snapshot but in 21w44a this appears to have been fixed!! 

High similarity with MC-166508, this is a duplicate!

This is not!

(@Dhranios)

Fixed, game internals use biome name instead of whole biome list in code now

The lagspikes are severely increased in a world with extended world height: Try this 4080 block tall custom world in 21w38a 

I just noticed there are affected versions attached that don't even support datapacks increasing world height. Isnt this bug only noticeable in worlds with increased height?

There seems to be a switch from low to higher fps at a certain number of blocks vertically away from max y, at at 32 this is 2048 blocks.

Edit: oh the chunks unload

In 21w14a mojang added the "min_surface_height" tag which is for defining the starting height of the surface builder, this tag also configures the minimum surface builder height of Nether Biomes. This change adds a point of inconsistency with this bug: Being able to define minimum surface level height but not maximum surface level height.

Yes, what I said makes no sense. It's just an excuse to create another reason why this bug should be fixed 

Without stronghold the dimension is invalid, and will indeed "break" the JSON but this is WAI iirc

Note: FPS can also decrease depending on how many chunks are loaded. The longer you look at something the more chunks could get loaded, the lower your fps might become, after how many seconds should the measurements be taken? The balancing of cpu resources might have also changed a lot last snapshot, amount of chunks loaded (letter C) should also be reported.

I'd like to further maintain this issue since you are unable to further provide affected versions. Would you be okay with me taking ownership of this issue? If you say yes I'll request ownership of this issue in the Mojira Discord. Thanks!

I can reproduce this issue in 21w10a. Did you try updating gpu driver by the way? There is a chance your PC will meet requirements.

I made a mistake, there are particles in both 08b and 10a, when I was testing I had particles turned off in 10a 🙂
This issue is invalid

Can confirm, they dont show at all for me
 

@moesh

Hi! I've tested a little further, and terrain does render when looking down, could you retest? Try looking mostly horizontal. Here is a video: https://youtu.be/gqpWL0uRoYk 

I've done a code analysis for one of my issues (MC-217802) using the mojang obfusication maps:

//net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings

public int getMinBuildHeight() {
  return 0;
}
    
public int getHeight() {
  return 256;
}

This hardcoding of getMinBuildHeight() and getHeight() results in this bug

With surface level do you mean ± 63, where you can see the open sky?

Can confirm

Hi @unknown, thanks for making that clear, I've edited the issue a bit(before seeing your message), is it clear to you there still is an issue in your fix? As said in the edited issue, the "noise" min_y + height has a limit of 2031, which is 1 off, if I'm correct this 2031 should be 2032 just like the other "type" min_y + height. 

This has not been fully fixed! This has only been fixed for the "type" and not for "noise", even worse, now it's (noise) min_y + height < 2031 which should be min_y + height ≤ 2032.

Is indeed "fixed" for "type", max became 2032 for both positive and negative.