bad optimization in this beta/preview.
In the overworld, the FPS have a drop between 30-23 FPS.
In the nether, the FPS they drop a lot reaching up to 15 fps.
In the End, the FPS is a bit stable but compared to the previous beta, it suffers from a drop in fps depending on the situation.
For example, if the End is empty except for only the dragon, the fps rate is between 41-29 fps.
If the End has mobs or entities the End has a fps rate of 36-25 fps, including the Ender Dragon, if there are only endermans or other mobs/entities there will be a small fps boost.
Also having items like patterned banners causes the game to freeze momentarily.
Thank you for your report!
However, this issue is Invalid.
Simply stating that "My game is laggy" is not helpful for Mojang to diagnose your issue. If you can pinpoint a specific cause when lag happens for you, please open a new report for that specific issue. If you think this might be a hardware issue please contact Community Support as they might be able to help with your issue.
Keep in mind that Mojang is constantly optimizing the game and simply playing the game provides feedback to Mojang on which parts cause performance issues.
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