When a mob is tracking a player the FPS drops for an example a creeper chasing a player or players holding wheat or carrots with animals following. When a player kills that mob or the mobs loses track of the player the FPS goes back to normal.
I have to set the game to peaceful just to be able to play because the FPS is terrible with the monsters tracking me. I hope this gets fix soon.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-28028.
It has been linked to this report. If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
This report also relates to: MCPE-28022
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