I have a dataset with 2157335 entries, and I am performing IDW/Kriging to interpolate.

But the code is running very slow. I am not sure this is because of a large dataset or there is something wrong with my code.

    grd <- Sobj_SpatialGrid(ndvi_pts, maxDim=100)$SG
    response <- unclass(ndvi_pts@data)[[1]]
    ndvi_idw <- idw(response~1, ndvi_pts, newdata=grd)

or for kriging,

    kriging_result=autoKrige(response~1, ndvi_pts, new_data=grd, nmax=7)

I cannot see anything wrong with it and R doesn't show any error. It just keeps running with no sign of stopping.