This happens on all Versions, it happens near large masses of loose silt and it usually makes it better or worse depending on the weather. I believe that their properties of gravity are always in effect so they are always trying to fall, which would be good if it didn't use a ton of resources calculating where its supposed to move, when it cant. Of course the lower the specs the worse the effects but this is just an awful optimization issue, it does the same with liquids but when they are actually moving. I've Played on a rig running windows ten with Eight Cores @3.2GHz and 16GB of ram and a Radeon R7 200 series, and an older one running windows XP with 3.25Gb of ram an amd athlon 64 dual core @2.91Ghz and a Radeon HD 6700 Series. although the fps drops on the newer rig aren't as serious they were very noticeable and irritating, while on the other one, it was virtually unplayable. All my friends have said the same on the matter.