the reconstruction is suddenly very slow

Hi,

We have been using CC advanced for 2 years.

Now we are working on a large project to turn a site into a 3d model.
Because it is a large area, we have divided it into different zones that are approximately the same size. We were able to deliver the first 2 zones without any problems. Now it plots that we are starting on the 3rd zone, the reconstruction is very slow. In the previous zone, the time was approximately 24 hours, to produce +/- 35 tiles.
In the 3rd zone, it is only 3% of the 1st tile. We have not changed the settings and we use the standard method to process data. We cannot find the problem. Can anyone help us?

(we use a local coordinate system)