Solved! Go to Solution.
thanks a lot for your answers. Unfortunately neither converting it to a shapefile nor a larger XY tolerance worked. I guess it´s just too much for ArcGIS to handle.
I think the only solution is to split my dataset up in smaller chunks, do the geoprocessing and put those back together afterwards.
My theory is that the local RAM is spent, and if so there seems to be no good way to refresh the RAM mid-process. Anyone else experience something like this?