If you fill a chest to the brim with blocks/items, then have a hopper run into it with different blocks/items than the chest has, the hopper with consistently attempt to put those items from the hopper into the chest, causing placing, block, and sound lag. (Probally more too)
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Steps to Reproduce:

Get a chest (double or one), and place one of (for example) cobble stone in each slot

Then place a hopper going into the chest, with (for example) bricks in each slot

If you have multiple of theese, then the lag increases exponentially
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What should happen:

The hopper should stop attempting to put the blocks/items in, until there is a slot open for it to do so