I noticed how slow hoppers were in one of my superflat air worlds. I noticed a significant drop in speed in that world compared to others.

Expected:
Hoppers process items at the same speed in any kind of world, unless altered.

Found:
Hoppers in superflat air worlds process items slower than in default generated worlds.

How to replicate:
1. Generate a superflat world with the preset 2;0;1
2. Do /setblock ~ ~-1 ~ stone
3. Set up a hopper clock, with both of them feeding into each other.
4. Put a single item in one of the hoppers.
5. Put comparators leading out of both the hoppers. Notice how slow they are compared to the same hopper clock in a normal world.

To compare, simply set up the same hopper clock in a default generated world.

Here is a link to the bug being proven:
https://www.youtube.com/watch?v=WzbN7DLmx4s