150ms is huge given latency within a EC2 region should be a millisecond or less, although I suspect this could be working similar to BetFair where they internal

150ms is huge given latency within a EC2 region should be a millisecond or less, although I suspect this could be working similar to BetFair where they internally queue and process the orders in a batch every 200/250ms rather than real time whilst giving the appearance of real time ('taker' being matched within the first batch since queued).