Minecraft hopper mechanics

Question

I've been working on quite the sorting system, which basically sorts every stackable item in the game. I've been noticing a few performance issues when I enter the area (Lower fps in general).

Now I've heard something about covering up all the hoppers to increase performance, since they will stop checking for items on top of them when they have a block placed there. I have read the wiki, but my English isn't that great, and I couldn't make up if this is true or not. Does someone know if this is true or not?

I could try to just cover them all up, but since it's rather large, I'd prefer to know for sure before I cover up 1000+ hoppers

Answer 1

Hoppers will try to look to the block above it, and see if there is an item there. However, two conditions can prevent this from happening.

1. If the block above it is solid (e.g. no slabs, stairs, etc.), and isn't a container (e.g. chests, furnaces, other hoppers), the hopper will not check for items.

2. If the hopper is not close to spawn, and the player is far enough away from the hoppers, the chunks will despawn, and the hoppers will not be able to check.

Just placing any normal block over the hoppers should work.

Reference: https://minecraft.wiki/w/Hopper

Answer 2

Yes that is true. As long you place a block with a container (eg. furnace, dropper) on top of the hopper, it will reduce the needed calculations for the hopper up to 80%.

Answer 3

Hopper will sometimes keep extra chunks loaded. If a hopper is "pointed" towards a block that is in a different chunk, this will keep the adjacent chunk loaded as long as the hopper chunk is loaded. Depending on the size of your machine, this could be anywhere from zero to dozens of extra chunks. By using the debug text you can find the edge of chunks and make sure your machine doesn't have hoppers crossing into other chunks. Simply moving your machine over a block or two might do the trick.