There&#x27;s a per-invocation cost that, at ridiculous volumes, becomes non-trivial ($0.20 per million). We get very high throughput (my back of the envelope math says about 3 writes per millisecond per Lambda, that&#x27;s to a Cassandra cluster) for I&#x2F;O intensive operations. You can have up to 100 simultaneous invocations, and you can ask for more (we did). Without knowing more about your situation, I would suggest that you use a library that lets you fire off a bunch of async requests and block on them all. Play around with RAM&#x2F;CPU (one knob for both)--a higher setting may result in quicker processing at a lower cost (!). If you&#x27;re highly cost sensitive, consider batching your SNS messages--remember that it supports 64K payloads. (We use SNS to do batchloading, actually--it&#x27;s a cheap, managed alternative to Kinesis.)<p>Should you choose the fanout route, Tim Wagner from AWS told me that it&#x27;s pretty fast: <a href="https:&#x2F;&#x2F;twitter.com&#x2F;timallenwagner&#x2F;status&#x2F;658025794900365312" rel="nofollow">https:&#x2F;&#x2F;twitter.com&#x2F;timallenwagner&#x2F;status&#x2F;658025794900365312</a>