I created a field with sugar canes and blocks above it. This is how that bar behaves when looking directly at it.

 

Issue is that the FPS drops and that constantly unless facing away from it, even if solid blocks are covering it.

 

 The water has 2 blocks underneath it, because otherwise it caused particles and lag even more.

 

 

 

The other test, was a tiny bit less laggy. Here I covered the entire field with blocks and ontop put a few more layers of blocks. I made a hole to expose the crops to see how the FPS behaves.

 

 

 

 

 

If I look down while I'm on the "surface" of the field area that is two blocks height, this is how the FPS behaves:

 

 

In the test where I covered all the blocks, if I look down it is similar aswell:

 

for some reason even worser

 

 

If I go under the field it won't lag even if I look at it while underneath it, which is interesting and weird and I wonder why.

 

 

I've provided the *test world* in the *attachments*, so that everyone can test it aswell. The field is in total 161x161 big. And 159x159 is basically the inner size of the crops and all. Incase you want to add more layers accurately. Both fields start at the corner of a chunk.

If I read through the internet, this issue started to happen for people since 1.14, when VBO was removed. Unsure how it worked though. However it could be that something else can be done about this aswell, since it can not be added back and maybe there are better ways to fix this issue.

 

This occurs in both 1.16.4 and 20w51a. In 20w51a the new "Sculk Sensor" causes a simillar issue aswell. Or Nether Wart and more, unsure about Wheat. Seagrass may cause a similar issue aswell.