I have layer of 164000 buffers (buffer of 1km generated around a point) which is to be clipped by one or more of approx 1.2 millions polygons representing green areas. Most of the green areas do not intersect with buffer. I want to calculate the combined area of the green areas within the buffer. The buffer layer contains an attribute table with 164 000 rows.

How do I get a result attribute table from the buffer layer with an additional column of the area of the green areas within the buffer?

I have tried the clip function i QGIS, but it takes forever on my dataset and I had to abort. I tried halving the datasets in the layer, but still no results within many hours.

I tried doing this in R with the st_intersection function, but I got more than 164000 rows. I want only the rows in the buffer with one or additional columns representing the area.

And solution in QGIS or R would be greatly appreciated