Work with point cloud.

Hey everyone,
I want to create a polysurface from a point cloud.
But my point cloud is very big. To create a mesh from the point cloud is no problem, now. And to make it faster i want split the point cloud or the Mesh.
Promlem is that the mesh or the pointcloud is open and i don't know how i can close this.
Has anybody an idea what the best way is?