The bug
Large numbers of tile entities holding special renderers cause major FPS drop.
Affected blocks:
Banner
Bed
Bell
Chest & Trapped Chest
Conduit
Decorated Pot
Enchanting Table
Ender Chest
Head & Skull
Moving Block & Moving Piston
Shulker Box
Sign & Hanging Sign
Related issues
Attachments
Comments


All these items didn't really seem to affect the fps.
[media]
I got an FPS difference, but not that extreme with 2601 chests - from ~600 FPS to ~550. I think it depends on your computer's RAM, CPU and GPU.

Side note, mods such as Enhanced Block Entities already tries to solve this issue while preserving vanilla animations and mechanics. Not promoting it or anything, but just saying that performance optimizations for these sorts of blocks already exist. 🙂
And yes, I can confirm this issue, especially on my old laptop.

@unknown For me its a little different, whenever I hold one of the items mentioned it seems like my fps increases rather than dropping.
For the rest of these please make individual bug reports unless told otherwise