Problems creating large number of documents

I have been running some tests around performance and ran across a problem attempting to create a large amount of documents. I have broken this down to the simplest example I can think of (see below) and been unable to insert more then 300 documents at a time. I have been able to rewrite the below as a recursive call but this is not ideal. I accept that this might not be a realistic example but do think that this is something which should be able to be done.

var driver = require('couchbase');

var config =

;

driver.connect(config, function(err, couchbase) {
console.log("connected");
for(var i=0; i < 300; ++i){
couchbase.set("new_"+i, "something", function(err, meta)

);
}
});