I don't remember in what version this issues is started, but in the current one (1.14.3) my world lags so much.
The problem are the chests, when I look at them, the FPS drops a lot, while if I look away the fps are higer.
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It seems to have gotten worse in 1.16.100 and even worse in 1.16.200 since I had an autosorting room that prior my PC could easily run at 144fps. 1.16.100 arrived and it was down to about 100-110fps, and 1.16.200 I was around 70fps.

Is this an issue still in the newest version? If yes, then could you add it to the affected versions, or mention it, if you are a commenter?

I experienced something similar in my test world, but my FPS drop was not as severe as you describe.
Can you attach the world affected?

Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
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Re-resolving as a duplicate if MCPE-137537.
For me the game engine seems to lag rather than my actual pc (1000$ gaming pc)
so mobs act unusually slow and stuff...