AnvilPuncher

Thank you for the reply. I am editing the view view-distance property in the server.properties file. Originally, I set it to 6 (chunks) so that there would only be roughly 169 chunks open per player. This tested fine in the get go because I hadn't tested it over distances traveled. Later, there came to be expanding memory use coupled with crippling lag over time. I had figured that this was due to the many mods I was using at once. I had done extensive testing with java optimizations that did seem to work some but did not stop the ballooning memory consumption and lag. Eventually, I suspected chunks were not unloading and installed ProfessorMobius's Opis because it gives chunk data and a graphical map. Sure enough, after travelling a few hundred chunks in one direction, there were ten thousand chunks counted and the graphical map showed a trail of open chunks. There was only one player (the operator) and these chunks persisted after hours of wait time. Afterward, the view-distance in server.properties was set to 10 and then tested. The chunks were only loaded around the players and it wouldn't leave a trail of them when travelling.

While using Forge version: 10.12.2.1147 (server, windows), chunks loaded naturally by players will not unload. This, of course, would cause many thousands of chunks actively open without ever unloading until the server was restarted. The server.properties view distance was changed to 6 from its default. It was having the view distance changed to a low number that caused this behavior. While this has an obvious work around, it was an insidious bug nonetheless due to the view distance property being reduced a natural "fix" for high tick times. Changing the view distance to 10 made the chunk unloading work correctly. Other values or versions were not tested. This behavior was noted on a fresh install of the above version without other mods on the server. This post was created so that other users may be able to search and find this fix as well as to note this behavior to the maintainers of Forge.