Severe performance drops when looking at bodies of water

When looking at bodies of water, performance drops significantly. See attached photos for FPS display from Preview version.

This does NOT happen when submerged. Performance returns to a stable level.

Steps to reproduce:

1. Create a world on Minecraft Preview (for FPS display) in creative mode and find any large lake, River or ocean.

2. Stand at the edge of land facing water, turn off Volumetric fog and Reflections then observe your FPS. Turn back on these two settings and observe your FPS again.

3. do a 180 degree turn and observe your FPS when looking away from the water. (Facing Land)

Observed results - FPS drops by up to 30 frames while looking towards the body of water and quickly returns to normal when looking away. This is not because of SSR or volumetric fog as when these settings are OFF or set to LOW there is no improvement in performance.

Expected results - performance would understandably drop if SSR or Volumetric fog were the reason. Although that is not the case. So I should be observing a steady 50-60 frames per second when both looking at land AND water.