@@Ramikad saw this on one forum: Increasing the _blocksize in the world spawn is something I have used on large open maps, large terrain maps, etc... Blocksize is automatically 512. Meaning that every X unit, q3map2 will automatically create portal splits on X Y Z. This is why large open maps benefit from a larger blocksize. If you have 512 blocks split on a huge map, vis data can pile up pretty quickly.