Ran on my macbook air, half a million docs. Single node, 5 primary 0 replica. Node restarted between runs to make sure all caches cleared, etc.
$ python loadtester.py --es "http://localhost:9200/speedtest/_search" -i ../data/stoicism.txt -o test1.txt --ns 10000 --nt 3 --nf 10
0 26004 1.36110687256
1000 5561 0.0182199478149
2000 10516 0.0134048461914
3000 42137 0.0833399295807
4000 34922 0.0168430805206