Sudden FPS drops since 1.15

This issue happens since 1.15, the better performance update. It makes it annoying when playing custom maps.
Here are some videos of the Pyramid parkour map in different versions
Performance 1.16 (Pre-release 5) https://youtu.be/8sdcc5-Mm5k
Performance 1.15.2 (with Optifine): https://youtu.be/vZRK5UIvZKc
Performance 1.14.4 (with Optifine): https://youtu.be/0qJNqJnqW3Q