I tested and this server has around 5,000 datablocks, by the time my client finished loading datablocks Blockland was already using around 2.5GB of Vram. When I spawned I got up to nearly 4GB of Vram, (4.5GB with shaders enabled). It's entirely possible that you were just on the edge of using your maximum Vram and having a few more player models or particles spawned caused your Vram to go over and cause the game to crash. I would recommend turning down your texture quality, particle settings, and/or view distance.