I confirm that the water system and the palm tree used are the source of the “metronome” because I can not reproduce the issue when i use a map without water system with this palm tree (market place => tropical foliage) .
Anyway I have solved the issue by setting the “sway amount bounds” in the foliage and trunk textures used for the palm tree to 0 ( instead of 0.001 )
See picture below:
