In a transaction system, a dynamic batching process enables efficient flushing of data in a data buffer to a stable storage device. The transaction system uses constant values and dynamic values and a system performance history to adjust the rate of flushing data and also to adjust the amount of data flushed in each flush operation. The transaction system is able to respond to both spikes in rate of received transactions as well as more gradual changes in the rate of received transactions and to automatically adapt to stable storage device performance variations.