high latency on elasticsearch requests - elasticsearch

Question

I am using the Transport Client to index data. Here's a small test program:
#Test
public void LatencyTest() throws Exception {
// warmup
for (int i = 0; i < 10; i++) {
client.prepareGet("ts_head", "doc", "latency_test_id").get();
}
List<Long> times = Lists.newArrayList();
for (int i = 0; i < 100; i++) {
final long t1 = System.nanoTime();
final IndexResponse response = client.prepareIndex("ts_head", "doc", "latency_test_id").setSource("{}", XContentType.JSON).get();
final long t2 = System.nanoTime();
times.add(t2 - t1);
}
final double average = times.stream().mapToLong(v -> v).average().getAsDouble();
System.out.println("Average time: " + (average / 1_000_000f) + "ms");
}
the output is: Average time: 79.3905588ms, which seems awfully slow. It accesses a cluster consisting of 2 nodes (both master) over a local network with a gigabit connection. The network itself doesn't seem to have high latency:
$ ping -U 172.***
PING 172.*** (172.***) 56(84) bytes of data.
64 bytes from 172.***: icmp_seq=1 ttl=128 time=0.324 ms
64 bytes from 172.***: icmp_seq=2 ttl=128 time=0.280 ms
64 bytes from 172.***: icmp_seq=3 ttl=128 time=0.348 ms
64 bytes from 172.***: icmp_seq=4 ttl=128 time=0.306 ms
Indexing via HTTP is pretty slow as well:
$ curl -w "#curl-format.txt" -X POST -s "http://172.***:9200/ts_head/doc/latency_test_id" --data '{}'
{"_index":"ts_head","_type":"doc","_id":"latency_test_id","_version":211,"result":"updated","_shards":{"total":2,"successful":2,"failed":0},"created":false} time_namelookup: 0,001381
time_connect: 0,135607
time_appconnect: 0,000000
time_pretransfer: 0,136056
time_redirect: 0,000000
time_starttransfer: 0,283840
----------
time_total: 0,284044
Now my question is: What am I doing wrong? Elasticsearch must surely be capable of indexing faster, right?
For testing, I also read data, and it reported "took": 1, but still too consistently over 100ms to respond via curl.