Minecraft 1.14 Pre-Release 2
OS: macOS 10.13.6
JRE: Minecraft bundled Java runtime
On average I get around 75 fps but when chopping trees (especially ones with large amounts of leaves such as dark oak and jungle trees), my frame rate tanks anywhere from 2-10 fps. The issue persists until all leaves have decayed. The closer to the decaying blocks I am, the worse the drop in frames. This is especially bad in jungle biomes when lots of leaves are updated from a single tree decaying.
The three attached images show fps graph before the logs of trees have been destroyed, looking at the decaying leaf blocks from a distance, and standing next to the decaying leaf blocks.
CPU: Intel i7-6700k
GPU: Nvidia GTX 1060
1. Chop down trees and wait for leaves to begin to decay.