A method for data storage includes providing a memory, which includes first memory cells having a first reading latency and second memory cells having a second reading latency that is higher than the first reading latency. An item of data intended for storage in the memory is divided into first and second parts. The first part is stored in the first memory cells and the second part is stored in the second memory cells. In response to a request to retrieve the item of data from the memory, the first part is read from the first memory cells and provided as output. The second part is read from the second memory cells, and provided as output subsequently to outputting the first part.