increased performance with repetition

I've been running a few tests using the Couchbase 1.8 server and comparing it with a memcached server, using both the CouchbaseClient (on the Couchbase server) and the spy MemcachedClient(on both servers). Over 1000 repetitions of a cache.getBulk(collection) call surrounded in time stamps, the time stamps claim the calls are getting quicker the more iterations run.

This happens during all three trials, with both clients and both servers.

I am running both the client and the server locally on my Windows machine.

The first call takes about 9-10 milliseconds to complete (from previous reading this is expected), then the numbers drop to 0-3 ms with most occurring in the 1-2 ms range. However, after about 200 iterations, the CouchbaseClient and the MemcachedClient(running on the Memcached server) getBulk() calls drop to between 0-1 ms. The MemcachedClient(running on the Couchbase server) hits the 0-1 ms mark a little bit later, around 400 iterations.

I can't figure out why the fetches keep getting faster and faster. Any light shed on the matter will be greatly appreciated.

	Collection<String> collection = new HashSet<String>();
 
	collection.add("p1");
	collection.add("p2");
	collection.add("p3");
	collection.add("p4");
	collection.add("p5");
 
	Map<String,Object> m;
 
	/////////////////////////////
	//time stuff
	start = System.nanoTime(); 
	m = cache.getBulk(collection);  		//call to cache
	finish = System.nanoTime();
	total = Math.round((finish - start) / 1000000); //convert to ms
	fileWriter.write(total + "\r\n");
	////////////////////////////