The standard magento way to sync orders placed, to external systems, is to use the 'sales_order_place_after' event. (This is even a question in the magento certification exam)

I have a problem with this: latency at checkout!

Using this (presecibed) method to sync your orders, you can add at least 3+ seconds (and as long as xx seconds) to the checkout process. That is unwanted lag, and delay for your customers, just to se their success page display.