When I'm in my survival world approaching trees and especially when i start to cut down the leaves, or the wood the frames drops from a consistent 50 - 60 FPS to 3 - 25  FPS and varies greatly. It varies between 55 and 3 FPS and one second it is 3 FPS, the other second 50 FPS so it has constant lag spikes. When i run away again me FPS starts to stabilize (it doesn't stabilize directly though, it takes a few seconds) When i turn around and look at a tree farm (with about 80 oak trees) the lag returns. It also lags with single trees not in farms. When playing in windowed mode the lag spikes are somewhat better but don't go away completely, there are less lag spikes and they are less great but they do stay. I don't think it's a full fps problem because the game sometimes outputs 50 FPS according to the F3 screen but freezes for a split second.