Since the 1.16.220 update, I am encountering massive frame drops occasionly in local worlds. Every frame drop lasts for about 5-10 minutes (lagging my whole system and hogging 100% CPU at the beginning) and drops to fps as low as 12-15.
The drop persists even when both CPU and GPU are not fully loaded like you can see in the picture attached.
The drop seems more likely to happen in jungles, but can also happen in other places rarely.
Minimizing minecraft for a few seconds then maximizing it fixes the drop (until the next one happens). Before the 1.16.220 update I used to get solid 60 fps while hosting worlds, now it is becoming an annoyance dropping my PC to performance lower than my low end mobile. My PC specs: Intel core i7-8565U Nvidia Geforce MX130.
Update on the matter:
It seems that the issue is in my system not in minecraft (I thought it is minecraft but turns out that minecraft is the only app I use that loads the PC so hard to trigger this behavior), doing more tests I found out that my CPU during these lag spikes is running at 400MHz which is what is slowing down my system to a halt. Sorry for the inconvenience...