Well, after updating the server to CB 1.7.2 dev build I came across a problem: sudden increasing of RAM usage. During fist 2-5 hours of uptime server works normal, with 3-4G memory usage. But then it starts using a lot more memory than usual - it increases from 3G up to 16G during ~30 seconds, and this causes enormous lags. For example: I have a new-generated map on the server, not from older versions (1.6 and lower). Tried to disable generate-structures option - nothing changed. Tried to fix all chunks on map with the help of Region Fixer - the problem still exists. Tried using VisualVM, make a heap dump and see, what classes overload RAM, here it is: How it works after start, with 20-30 players online: What happens next: Perhaps, something is wrong with DirectByteBuffer and ChannelOutboundBuffer$Entry classes, as you can see in this screenshots. So, has anybody got the same problem? What should I do to fix this issue? Such enormous memory usage is not OK.. Hope for developers advice..