[2021] Server Reboot Purgatory

See these changes in 19.5 release notes.

Voxel mesh pooling

Distant terrain decreases mesh detail when farther

FindTagInChilds does not make garbage

Distant POIs to use a shared material

Improved chunk LOD update

Optimized chunk object handling and frame timings

Optimized terrain mesh generation

Optimized terrain control textures to not update with every mesh update

Optimized distant terrain tile size

Optimized VoxelMesh AddMesh

Optimized distant terrain render order

Block preview for normal blocks leaking a mesh on each