I had to reduce the batch-size to 512, because otherwise sort complained with batch-size too large. The timings are: real 30m54.557s user 82m9.055s

I had to reduce the batch-size to 512, because otherwise sort complained with batch-size too large. The timings are: real 30m54.557s user 82m9.055s sys 3m1.723s no improvement over sort without the batch-size...