Having the unbreaking enchantment on equipment such as an axe, a pickaxe, or a shovel causes lag when using these tools to break a bunch of blocks in rapid succession.

The intended result of using unbreaking on a tool is to use the tool longer than normal.

The bugged result allows the tool to be used longer, but causes lag while in use.

To reproduce the bug, simply enchant a pickaxe and mine away at blocks for a time. (To see the bug more often, also have efficiency V.)

In comparison to a pickaxe with just efficiency V, a pickaxe with unbreaking (any level btw) and efficiency V causes significantly more lag.

This comparison can also be made among each tool the can mine blocks fast.

I am unaware if this bugobug on other platforms, but it certainly BUGS me on my ps4.