As I noticed, trying to develop basic random teleportation plugin on Spigot 1.13 - new core takes about ~50x more time to generate new chunk, then on Spigot 1.12.2, that causes a lot of lags, as all computations can be done only in main server thread. Code (Java): World world = .... Chunk chunk = world.getChunkAt(x, y); Measured by System.currentTimeMillis, so results are not accurace, but just compare: Spigot 1.12.2 b1573-c takes about 20-80ms to perform that operation Spigot 1.13 b1767 takes about 500-1000ms to perform same operation All chunks were new, from clear map. Also I noticed huge tps drops on 1.13 (measured by React plugin) when just flying in normal speed and server crash on other server with 512Mb with a reason: GC Overhead Limit. As cyperpwn (the developer of React plugin) said to me: That situation makes much harder to host a server in 1.13 for now. It needs huge optimizations and at least async chunk generating (not loading) for my mind. Any comments, @md_5 ?