The bug

When particles of some not-full-blocks (list below) are created the game gets a lag spike for a few seconds. The lag is more and more noticeable the more and more the not-full-block that created the particles has other not-full-blocks nearby.
I can't exactly understand which blocks are affected by the lag, but these are the ones I found: chest, trapped chest, hopper, anvil, brewing stand, cauldron, piston and sticky piston head, extended piston and sticky piston (but not not-extended pistons), end portal, end chest.

How to reproduce

(optional: open Alt + Shift + F3)

1. Place a chest with other adjacents chests to create a star-shape (2017-11-22_16.58.10.png)
2. Jump on the middle chest from 30 blocks above (2017-11-22_16.58.10.png)
   As I said the lag comes even with a single tile entity, but it might be necessary to open Alt + Shift + F3 and look at the fps-graphic to notice it.