Hey,
My minecraft on 1.14 always worked great with atleast 200 fps.
Now that I play on 1.15.2 I sometimes get 150 fps but sometimes 30 fps.
My specs are:
i7-9900K
NVIDIA GeForce RTX 270 Super
16gb ram
Windows 10 pro
Linked issues
Comments
It is mostly everywhere. One moment I have 100 fps and then I start flying around and after a while my fps become around 30. I think its mostly around villages.

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Can you make out in which environment you have the performance hits?